03 Chikungunya Hills 508

Chikungunya epidemiology in U.S. territories and
states with risk of transmissionNational Center for Emerging and Zoonotic Infectious Diseases
Susan Hills MBBS MTH
CDC Lead , Chikungunya Vaccines Work Group
Arboviral Diseases Branch
Division of Vector- Borne Diseases
Fort Collins, Colorado
ACIP Meeting, June 26, 2024
•Mosquito -borne disease
•Key vectors are Aedes aegypti
and Aedes albopictus mosquitoesChikungunya

•Typically tropical and subtropical
regions
•Periodically causes large outbreaks
-Often high attack rates
•Virus transmission usually highest
during wet seasonDistribution and disease burden in endemic areas
Countries and territories with current or past
transmission of chikungunya virus

•Febrile illness with typically severe
a
rthralgia, can be debilitating
•Other symptoms include headache,
r
ash, myalgia, anorexia
•No anti - viral treatment availableClinical features of acute chikungunya virus infection

•Rare serious complications (e.g.,
myocarditis, hepatitis, neurologic illness)
•Deaths rare and reported mostly in
-Older adults, particularly those with comorbidities
-Young infants infected perinatally or by mosquito bitesComplications of chikungunya
Images from : https://www.paho.org/en/topics/chikungunya
•Acute symptoms usually resolve in 7 –10 days
•Some patients have continuation or relapse
of symptoms
•Ongoing arthralgia of variable severity possibly present in up to ~50% at 3 months and ~30% at 12 monthsChronic arthralgia following chikungunya

Puerto Rico
•Largest U.S territory
-Po pulation ~3.2 million persons
-Area ~3,500 miles2
•Tropical climate
•Aedes aegypti pr esent
•Dengue endemic Puerto Rico

•Data from passive and sentinel surveillance systems
•No single data source provides accurate and complete information
•Surveillance activities, reporting practices, and laboratory testing
approaches changed during outbreak
-When laboratory capacity exceeded, testing prioritized for certain groups
-When number of suspected cases reached thousands per week, limitation on
types of cases to be reported
•Key points
-Numbers of cases often substantial underestimate of true cases
-Data provide reasonable representation of actual disease epidemiologyData sources
•Confirmed cases : detection of nucleic acid by RT -PCR
•Probable cases : IgM antibodies in serum or cerebrospinal fluid
•Chikungunya IgM antibodies can persist after acute infection
•13–18 months: 56% with IgM1
•2–3 years: 11% with IgM2 Laboratory criteria for chikungunya cases
1. Grivard  et al, Path Biol 2007;    2. Costa et al, Rev Soc Bras Med Trop 2021
•Chikungunya emerged in 2013
-First case reported in Saint Martin island in December
•Rapid increase in countries and territories reporting transmission
•In Puerto Rico, first laboratory -confirmed case in May 2014Chikungunya emergence in the Caribbean
Chikungunya cases reported by year and case status,
Puerto Rico, 2014 –2020
0200040006000800010000
2014 2015 2016 2017 2018 2019 2020Probable
Confirmed
Chikungunya cases reported by year and case status,
Puerto Rico, 2014 –2020
0200040006000800010000
2014 2015 2016 2017 2018 2019 2020Probable
Confirmed
Last laboratory -confirmed
symptomatic clinical case
Chikungunya cases by month of illness onset during
two main outbreak years, 2014 –2015
050010001500200025003000
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2015 2014
Chikungunya cases by sex, Puerto Rico, 2014 –2020
(N=10,293)*
Sex No. (%)
Female 5,116 (52%)
Male 4,708 (48%)
*n=469 with unknown sex
Chikungunya cases by age group, Puerto Rico, 2014 –
2020 (N=10,293)*
Years No. (%)
0–19 4,328 (42%)
20–39 2,055 (20%)
40–59 1,931 (19%)
≥60 1,865 (18%)
*n=114 with unknown age
Chikungunya cases by municipality, Puerto Rico,
2014 –2020

•Household cluster survey among persons aged 1– 50 years in one
municipality in southern Puerto Rico in 2018– 2019
-31% seroprevalence1
•Samples from blood donors aged ≥16 years collected in March 20152
-23% seroprevalence2
•Based on 30% seroprevalence rate, ~ 1 million persons estimated to have
been infected  during outbreak
-~650,000 –85 0,000 clinical cases Proportion of Puerto Rico population infected
1. 1,268 of 4,035 participants (Adams LE at al, PLoS  NTD 2022);     2. 242 of 1,031 samples (Simmons G et al, Emerg  Infect Dis 2016)
United States Virgin Islands (USVI)
•First locally acquired case detected in
early June 20141
•Initial transmission on Saint ThomasInitial transmission of chikungunya in USVI
Source: https://ontheworldmap.com/virgin -islands- us/
1. Feldstein LR et al, Am J Trop Med Hyg 2016
Epidemic curve of chikungunya cases* by island, USVI,
2014 –2015 (N=637)
*Confirmed or probable Feldstein LR et al, Am J Trop Med Hyg  2016
Last laboratory -
positive case
February 2015
•31% persons had evidence of past infection in seroprevalence survey
approximately 1 -year post -outbreak1
•~33,000 persons estimated to have been infected during outbreak
-~21,000– 28,000 clinical cases during 8- month  outbreak periodProportion of USVI population infected, 2014 –2015
1. Hennessey MJ e al, Am J Trop Med Hyg 2018                    *Laboratory confirmed or probable
Other U.S. territories and freely associated states
•American Samoa1
-Outbreak began June 2014
-Unconfirmed information suggested ≥823 suspected cases
-Unclear duration but no evidence of transmission by end of 2015
•Guam and Commonwealth of the Northern Mariana Islands (CNMI)
-No cases reportedOther U.S. territories
1. Roth A et al, Eurosurveillance 2014; ArboNET  data
•Federated States of Micronesia (Yap State)1
-Outbreak from Aug 2013 –Aug 2014 with peak Oct –Dec 2013
-1,761 suspected cases reported
-Attack rate of 155 clinical cases per 1,000 population, so ~15% population sought
care for suspected illness
•Marshall Islands2
-Outbreak began February 2015
-Unclear duration and extent but unconfirmed information suggests >1,000
suspected cases
•Palau
-No cases reportedFreely associated states
1. Pastula DM et al, PLoS  NTD 2017; 2. Ministry of Health Republic of the Marshall Islands Chikungunya Report, April 2015.
•3 territories and 2 affiliated states have had chikungunya outbreaks
•Outbreaks were explosive
•For Puerto Rico and USVI, ~30% of population was likely infected, with
20% –25% of the population having clinical illness mainly during a period ~6
months
•All outbreaks began 2013– 2015
•No evidence of confirmed transmission since 2017 (Puerto Rico) or earlier
in islands with smaller populations
•Timing of future transmission or outbreaks and likely pattern unknown Summary:
Chikungunya in U.S territories and affiliated states
Locally -acquired cases in U.S states
Aedes aegypti           Aedes albopictus  Estimated potential range of Aedes aegypti and Aedes
albopictus in the United States, 2017
https://www.cdc.gov/mosquitoes/php/toolkit/potential -range -of-aedes.html
•First local transmission of chikungunya virus in
c
ontinental United States was in 2014
•Occurred in context of chikungunya outbreak in
Ame
ricas and increase in traveler cases
•After 1st locally -acquired case in June, 11 additional
cases identified in 4 counties in southern Florida
•Two patients lived within 1,500 feet of each other and
o
ther cases were sporadic reportsFlorida (N=12)*#
*11 cases described in MMWR and one case reported after MMWR published
#Does not include one case from different area of Florida published by clinician in 2021 (Am J Emerg
Med, 2021) as IgM positive result not confirmed when tested by neutralizing antibody testing
Kendrick K, et al. MMWR 2014;63(48):1137
Texas (N=1)
•One case in Cameron County
•Occurred in November 2015
Mexico
Location of Cameron County, Texas
For more information, contact CDC
1-800- CDC- INFO (232 -4636)
TTY:  1 -888- 232- 6348    www.cdc.gov
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.
Acknowledgments
•Puerto R ico Department of Health
•Nicole Lindsey, Arboviral Diseases Branch
•Laura Adams, Dengue Branch
•Joshua Wong, Dengue Branch

Summary: Chikungunya epidemiology in U.S. territories and  states with risk of transmissionNational Center for Emerging and Zoonotic Infectious Diseases Susan Hills MBBS MTH CDC Lead , Chikungunya Vaccines Work Group Arboviral Diseases Branch Division of Vector- Borne Diseases Fort Collins, Colorado ACIP Meeting, June 26, 2024 •Mosquito -borne disease •Key vectors are Aedes aegypti  and Aedes albopictus mosquitoesChikungunya   •Typically tropical and subtropical  regions •Periodically causes large…


04 Chikungunya Kilburn 508

1
Cost -effectiveness of live attenuated chikungunya vaccine among adults
living in US territories
Kelly Kilburn, PhD, Martin I. Meltzer, PhD, Seonghye Jeon, PhD, Susan L. Hills, MBBS,
MTH, Bishwa B. Adhikari, PhD, Nicole P. Lindsey, MS, J. Erin Staples, MD, PhD
June 27th, 2024
National Center for Emerging Zoonotic and Infectious DiseasesNational Center for Emerging Zoonotic and Infectious Diseases

2•Authors have no known conflict of interests
•The findings and conclusions in this presentation are those of the authors and do
not necessarily represent the views of the Centers for Disease Control and Prevention.Conflicts of Interest Statement
3•Research question
•Methods
•Results
•Sensitivity analyses
•Limitations
•SummaryOutline
4•What is the cost -e ffectiveness of using a single dose of the live
attenuated chikungunya vaccine among the population aged ≥18 years
in US territories* that previously experienced an outbreak of chikungunya?
*American Samoa, Puerto Rico (PR), and US Virgin Islands (USVI)Research Question
5Methods
6•Population- based model
-Entire population of three US territories in model
•Time step: 1 year
•Analytic time horizon: 30 years starting in 2024
•Discount rate: 3%
•Perspectives: societal and healthcare payer
•One chikungunya outbreak occurring in 2034Economic Model
7•Use of live-attenuated chikungunya vaccine
Strategy 1:
Routine VaccinationStrategy 2:
Outbreak Vaccination
Annual Vaccination Yes No
Coverage rate1 20% --
Outbreak campaign in 2034 Yes Yes
Coverage rate2 70%3 70%
1 Routine coverage rate range based on annual influenza vaccine uptake in Puerto Rico (CDC data)
2 Outbreak coverage rate range based on Covid -19 vaccine uptake in Puerto Rico (CDC data)
3 Total coverage rate for outbreak year considers routine vaccinations from all prior years and vaccinations during outbreak. Individuals are vaccinated only once.Intervention
8Routine strategy
Initial vaccination
of target populationOutbreak vaccinationof target population
Vaccination of new 18 yo Vaccination of new 18 yo
Outbreak strategy
Outbreak vaccinationof target population2053
20532024
2024 20342034Strategy Comparison
9•Estimated population- level health outcomes
-Symptomatic cases
-Hospitalizations
-Chronic joint pain cases
-Deaths
-Quality -adjusted life -years (QALYs) lost
•Estimated economic outcomes
-Societal costs – vaccination, medical, and lost productivity costs
-Healthcare payer costs – vaccination and medical costsOutcomes
10•Calculated incremental cost -effectiveness ratios comparing
vaccination to no vaccination
-Measured as $ per each outcome averted (or QALYs gained)
•Monte Carlo simulation with 1,000 replications to estimate results
with 95% CIs using @Risk software
•Conducted sensitivity analyses (univariate and scenario)Analysis Approach
11Model Assumptions
12•Chikungunya virus infection confers lifetime immunity
•Outbreak would stop once certain level of population is infected
(halting seroprevalence)Lifelong Immunity and Halting Seroprevalence

13Model Inputs
14USVI – US Virgin Islands; PR – Puerto Rico
* Level of  population immunity from prior outbreak in adult population. By 2024, baseline seroprevalence
has waned to 28% in population.Variable Value Range Source
Low High
Baseline seroprevalence* 31% 18% 42% USVI1 and PR2 data
% symptomatic among infected 72% 53% 97% USVI data1Infection Inputs
1. Hennessey MJ, et al. Amer J Trop Med Hyg , 2018; 99:1321- 1321.
2. Adams LE, et al. PLOS NTD. 2022; 16:e0010416- e0010416.
15Variable Value Range Source
Low High
% care -seeking 43% 30% 82% USVI data1
% hospitalized*10% 5% 15% USVI data1
% with chronic joint pain+35% 19% 61% Metanalysis2
% death^ 1% 0.1% 3% PR data3
USVI – US Virgin Islands, PR – Puerto Rico
* of those seeking care
+ 6 months after infection
^ of those hospitalized1Hennessey MJ, et al. Amer J Trop Med Hyg ,  2018; 99:1321- 1321.;
Hennessey MJ, et al. Centers for Disease Control and Prevention, 2015.
2Lindsey NP. ACIP presentation. 2023
3Sharp TM, et al. J Infect Dis. 2016; 214: S475- S 481Health Outcome Inputs
16•Vaccine seroresponse rate of 96.3% (clinical trial data)1
•Decay in vaccine seroresponse rate of 5 percentage points every 5 years based on
other live  attenuated or chimeric vaccines2
1.Schneider M, et al. Lancet. 2023;  401:2138- 2147.
2.Lindsey NP, et al. J Travel Medicine. 2018; 25:tay108; Desai KL, et al.
Vaccine. 2012; 30:2510- 2515.40%60%80%100%
2024 2034 2044 2054Seroresponse rateEstimated Vaccine Seroreponse Over Time HorizonVaccine Seroresponse
17Variable Time Weight
(range)QALYs Lost
(range)Source
Non -hospitalized case*^ 7 days0.63
(0.19- 0.91)0.01
(0.002- 0.016)Dengue1
Hospitalized case* 14 days0.56
(0.19- 0.91)0.02
(0.004- 0.031)Dengue1
Chronic joint pain case 1 year0.76
(0.65- 0.90)0.24
(0.10- 0.35)Chikungunya and
rheumatoid
arthritis2,3
QALY – quality -adjusted life -year; QALY losses due to death are included and include loss
beyond time horizon of model
*Weights for acute disease based on dengue; no weights available for chikungunya^All symptomatic cases had QALY losses regardless of care -seeking behavior QALY Inputs
1 Zeng W, et al. Am J Trop Med Hyg. 2018; 99:1458- 1465.
2 Couzigou  B, et al. Am J Trop Med Hyg. 2018; 99:182- 190.
3 Sorensen J, et al. Value Health. 2012; 15:334- 339
18Sensitivity Analyses Methods
19•Univariate (one- way) analysis
-Varied one parameter at a time and calculated mean $/QALY gained using low (1%)
and high (99%) values of input distributions
•Scenario analyses
-Altered year of outbreak to 2029 or 2039 (base: 2034)
-Altered halting seroprevalence to 30%1 or 80%2 (base: 40%)
-Altered vaccination coverage
•Routine 10% or 30% (base: 20%)
•Outbreak 50% or 85% (base: 70%)
1 Hennessey MJ, et al. Amer J Trop Med Hyg, 2018; 99:1321- 1321 &
Adams LE, et al. PLOS NTD. 2022; 16:e0010416- e0010416
2 Jamaican MoH. JHLSIII, 2018Sensitivity Analyses
20Results
21•Outbreak strategy averts 67% of health outcomes
•Routine strategy averts 90% of health outcomes
040,00080,000120,000160,000200,000
Symptomatic Cases Hospitalizations Chronic joint pain Deaths QALYs lostNo vaccination Outbreak RoutineHeath Outcomes

22•More doses delivered in routine strategy during 30- year time horizon
than outbreak strategy
•Base scenario vaccination costs
•Routine strategy : $436 million
•Outbreak strategy : $356 million
*Vaccination costs include vaccines, administration, and adverse event costs
   All costs converted to 2023 $USVaccination Doses and Costs*
23Outcome StrategyTotal costs,
No vaccine
(millions)Total costs,
Vaccine
(millions)Difference
Societal Costs*Routine $566 $496 -12%
Outbreak $566 $547 -3%
Healthcare
Payer Costs^Routine $269 $465 73%
Outbreak $269 $449 67%
All costs converted to 2023 $US
* Societal costs include vaccination costs, direct medical costs, and indirect costs due to lost productivity.
^ Healthcare payer costs include vaccination costs and direct medical costs.Total Costs
24Symptomatic
CaseHospitalizationChronic joint
pain caseDeath QALY gained
Mean cost per outcome averted [95% CI]
Routine
StrategyCost
savingsCost
savingsCost
savingsCost
savingsCost
savings
Outbreak StrategyCost
savings$2,315
[$1K, $4K]$5
[Cost savings,
$200]$373,054
[$173K, $573K]$59
[Cost savings,
$1K]Cost -effectiveness, Societal Perspective
25*Presented from societal perspectiveSensitivity Analyses Results*
26$ 0 $ 5,000 $ 10,000 $ 15,000 $ 20,000Baseline seroprevalence
Proportion symptomatic
Cost medical, chronic joint pain
Proportion hospitalized
Proportion sought care
Vaccine cost
Cost medical, acute case
Proportion chronic joint pain
Time with joint pain
Cost lost productivity, acute case
Cost per QALY gainedRoutine Strategy
Outbreak StrategyTop 10 influential inputs, ranked by impact to mean $/QALY gained
Results not visible where the range
was < $0/QALY gainedUnivariate Sensitivity Analysis, Routine Strategy
27Routine strategy Outbreak strategy
Mean $/QALY gained
 [95% CI]
Outbreak occurs in 2029 Cost savings$3,829
[$3K, $4.6K]
Outbreak occurs in 2039 Cost savings Cost savings
*Base scenario had outbreak occurring in 2034Sensitivity Analysis for Outbreak Timing*
28•30% halting seroprevalence: all scenarios have net positive costs
-Low vaccination has the lowest cost per QALY gained
•40% halting seroprevalence (base value): high vaccination has net
costs, base and low vaccination result in cost savings
-Low vaccination has the lowest cost per QALY gained
•80% halting seroprevalence: all scenarios  result in cost savings
-High vaccination has lowest cost per QALY gainedScenario Analysis Varying Halting Seroprevalence and
Vaccination Coverage*
*Vaccination Coverage Rates:
Base vaccination= 20% routine, 70% outbreak; Low vaccination= 10% routine, 50% outbreak; High vaccination= 30% routine, 85% o utbreak
29Limitations and Summary
301. No efficacy or effectiveness data available for current vaccine; data planned to be
generated in post- licensure studies
2.Limited evidence on outbreak frequency (i.e., when and how many) in same
geographical locations
3.QALY health utility weights mostly from dengue as proxy since no weights determined for acute chikungunyaLimitations
31•Chikungunya vaccine use in US territories would avert 67- 90% of cases and
associated health outcomes versus no vaccination
•Cost of intervention would range from $356 to $436 million depending on strategy
used
•Routine strategy had cost savings for each outcome while outbreak strategy had
mostly net positive costs in base scenario
•Results most affected by baseline and halting seroprevalenceSummary
32For more information, contact CDC
1-800- CDC- INFO (232 -4636)
TTY:  1 -888- 232- 6348    www.cdc.gov
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position o f the Centers for Disease Control and
Prevention.

Summary: 1 Cost -effectiveness of live attenuated chikungunya vaccine among adults  living in US territories Kelly Kilburn, PhD, Martin I. Meltzer, PhD, Seonghye Jeon, PhD, Susan L. Hills, MBBS,  MTH, Bishwa B. Adhikari, PhD, Nicole P. Lindsey, MS, J. Erin Staples, MD, PhD June 27th, 2024 National Center for Emerging Zoonotic and Infectious DiseasesNational Center for Emerging Zoonotic and Infectious Diseases  2•Authors have no known conflict of interests •The findings and conclusions in this…


05 Chikungunya Hills 508

Next steps for the Chikungunya Vaccines Work GroupNational Center for Emerging and Zoonotic Infectious Diseases
Susan Hills MBBS MTH
CDC Lead , Chikungunya Vaccines Work Group
Arboviral Diseases Branch
Division of Vector -Borne Diseases
Fort Collins, Colorado
ACIP Meeting, June 26, 2024
•Work Group gathering data and will discuss additional important
considerations including:
-Acceptability and value of vaccine to providers and relevant populations
-Feasibility of administration Consideration of recommendations for use of
chikungunya vaccine in at -risk U.S. territories
Plans for development of vaccine recommendations
Populations Live
attenuated vaccine
Travelers Feb 2024
Laboratory workers Feb 2024
Residents of U.S. territories with risk 
Residents of U.S. states with risk 
Plans for development of vaccine recommendations
Populations Live
attenuated vaccineVirus -like
particle vaccine
Travelers Feb 2024 
Laboratory workers Feb 2024 
Residents of U.S. territories with risk  
Residents of U.S. states with risk  

Summary: Next steps for the Chikungunya Vaccines Work GroupNational Center for Emerging and Zoonotic Infectious Diseases Susan Hills MBBS MTH CDC Lead , Chikungunya Vaccines Work Group Arboviral Diseases Branch Division of Vector -Borne Diseases Fort Collins, Colorado ACIP Meeting, June 26, 2024 •Work Group gathering data and will discuss additional important  considerations including: -Acceptability and value of vaccine to providers and relevant populations -Feasibility of administration Consideration…


01 Denvaxia Bergren 508

June 26 – ACIP Meeting
Dengvaxia®Next Steps
Nicholas Bergren PhD, MBA
Director, Scientific and Medical Affairs
1
Internal
22021  ACIP  Recommendation  for Dengvaxia®:
ACIP recommends  vaccination  with the Dengvaxia® vaccine  for children  aged 9–16 years
having  evidence  of a previous  dengue  infection  and living  in areas  where  dengue  is endemic .
Dengvaxia® is recommended  as a 3-dose vaccination  series,  administered  6 months  apart  (at
month  0, 6, and 12)for the selected  pediatric  population . Evidence  of previous  dengue
infection,  such as confirmation  with previous  laboratory -confirmed  infection  or a highly
specific  serodiagnostic  test, will be required  among  eligible  children  before  vaccination .Dengvaxia® Indication, Schedule & Recommendation
USPI  Indication :
For the prevention  of dengue  disease  caused  by dengue  virus serotypes  1, 2, 3 and 4.
Dengvaxia® is approved  for use in individuals  6 through  16 years  of age with laboratory -
confirmed  previous  dengue  infection  and living  in endemic  areas .
USPI  Dosage  and Administration :
Three  doses  (0.5 mL each)  6 months  apart  (at month  0, 6, and 12).
Internal
3Dengvaxia® has been available globally since 2015 and was recommended by ACIP in 2021:
▪Efforts have been made to facilitate implementation of the ‘Screen & Vaccinate’ approach as recommended by
WHO in 2018, however demand for Dengvaxia®has been andcontinues to remain low globally and in Puerto Rico.
▪Despite an increased incidence of dengue in different parts of the world, Puerto Rico's Dengvaxia®Immunization
Program is the only public program currently in place.
▪Dengvaxia®is indicated for people with prior dengue infection and requires a 1 -year vaccination schedule to
complete the primary series.
▪Dengvaxia®is not intended for acute dengue outbreak control.Dengvaxia®Next Steps
Dengue Tetravalent Vaccine (Live, Attenuated)  [Dengvaxia®] is being discontinued due to low demand.
This decision is not due to any concerns regarding quality, safety or efficacy.
We have worked early with and continue to collaborate with the CDC to facilitate product utilization.
Dengvaxia® will continue to be distributed through public (e.g., VFC) and private markets globally (including
Puerto Rico where it is currently recommended by the ACIP) through product expiry.
The last doses of Dengvaxia®will expire at the end of August 2026. Given the 3-dose, 1 -year series needed for
full immunization, individuals should start the Dengvaxia® immunization series no later than August 31, 2025.

Thank you

Summary: June 26 – ACIP Meeting Dengvaxia®Next Steps Nicholas Bergren PhD, MBA Director, Scientific and Medical Affairs 1 Internal 22021  ACIP  Recommendation  for Dengvaxia®: ACIP recommends  vaccination  with the Dengvaxia® vaccine  for children  aged 9–16 years   having  evidence  of a previous  dengue  infection  and living  in areas  where  dengue  is endemic .  Dengvaxia® is recommended  as a 3-dose vaccination  series,  administered  6 months  apart  (at  month  0, 6, and 12)for the selected …


02 Dengue Wong 508

Update on Dengue Vaccines
Joshua Wong, MD
Medical Officer | NCEZID/DVBD/Dengue Branch
Meeting of the Advisory Committee on Immunization Practices
June 26, 2024National Center for Emerging and Zoonotic Infections
1
Dengue Epidemiology Globally
Countries reporting locally acquired dengue cases,
March 2023 –April 2024
Image from: https://www.ecdc.europa.eu/en/publications -data/countriesterritories -reporting -dengue -cases -march -2023 -and-april -2024 . Accessed 6/1/2024
Dengue cases in the Americas, 1980 –2024
Nearly 10 million cases reported in 2024 as of June 25.
Data from PAHO PLISA Health Information Platform for the Americas. https://www3.paho.org/data/index.php/es/temas/indicadores -dengue.html . Accessed 6/25/202402,000,0004,000,0006,000,0008,000,00010,000,00012,000,000Number of dengue cases
Year
Dengue Epidemiology in the U.S.
In the United States, dengue is endemic in
6U.S. territories and freely associated states.

Puerto Rico declared a public health emergency
due to a dengue epidemic in March 2024.
Weekly Arboviral Report – Week 23, Puerto Rico Department of Health, accessed 6/25/2024. https://www.salud.pr.gov/CMS/DOWNLOAD/9050
2023 cases 2024 cases Historic median Epidemic thresholdDENV infections in
Puerto Rico have
been above the
epidemic threshold
for 21 weeks.x 21 weeksNumber of cases
Week
Update on Dengvaxia in Puerto Rico
The first dengue
vaccine in Puerto
Rico was
administered on
September 7,
2022.
Images from: https://www.elvocero.com/actualidad/salud/administran -la-primera -vacuna -contra -el-
dengue/article_9c49436a -2e4f -11ed -beba -0bf2bccaeb1f.html Accessed 6/12/2024.
Since Dengvaxia vaccination began in Puerto Rico,
264 doses have been administered.*
13149264
050100150200250300
1 2 3Number of Doses  of Dengvaxia
Administered (cumulative)
Year
Data used with permission from the Puerto Rico Department of Health, Vaccine Program. Current as of June 24, 2024.
Since Dengvaxia vaccination began in Puerto
Rico, 145 individuals have started the series.
145
87
32
020406080100120140160
1 2 3Number of Doses  of Dengvaxia
Administered (cumulative)
Data used with permission from the Puerto Rico Department of Health, Vaccine Program. Current as of June 24, 2024.
Physician visit #1:
Initial evaluationLaboratory
testingPhysician visit #2:
Results follow -upVaccine clinic visit
Schedule 2nd and 3rd dosesMultiple visits to healthcare providers to determine eligibility
and start vaccination has complicated implementation.
Major barriers to uptake have included:
Prevaccination
Testing
Limited vaccine
messaging
Complex billing
processes
CDC has updated its website with information
on discontinuation of Dengvaxia.
Dengue Vaccine | Dengue | CDC
Update on Other Dengue Vaccines in the U.S.
Takeda voluntarily withdrew TAK -003 (Qdenga) from
FDA review in July 2023.
Takeda/Newsroom
The TV003/TV005 dengue vaccine is in late-stage
phase 3 trials.
•Developed by the US National Institutes of Health (NIH).
•Licensed to Merck in the U.S. and the Instituto Butantan  in
Brazil.
•Phase 3 trials in Brazil are ongoing.
•High efficacy and safety results during the first two year
follow -up period have been published.*
•DENV -3 or DENV -4 not observed during this period,
limiting evaluation of VE against these serotypes.
•Five year follow -up data expected later this year.
*Kallás , E. G., et al. (2024). "Live, Attenuated, Tetravalent Butantan -Dengue Vaccine in Children and Adults." N Engl J Med 390(5): 397 -408.
Image from: https://revistapesquisa.fapesp.br/en/butantans -dengue -vaccine -is-80-effective/  accessed 6/11/2024.

No dengue vaccines will be available in the
U.S. after the discontinuation of Dengvaxia.
•No dengue vaccines are currently under
review by FDA.
•The ACIP Dengue Vaccines Workgroup
group will be paused until new dengue
vaccines are submitted to FDA for
approval.

Conclusion
•Dengue cases globally are increasing.
•Puerto Rico has declared a public health emergency due to the
dengue epidemic.
•There will be no other vaccines available in the U.S. after
Dengvaxia manufacturing is discontinued.
•The Dengue Vaccines Workgroup will be paused until new
vaccines are submitted for FDA review.
•Vaccines are just one part of a multilayered approach to
reducing morbidity by dengue.
For more information, contact CDC
1-800-CDC-INFO (232 -4636)
TTY:  1 -888-232-6348    www.cdc.gov
The findings and conclusions in this report are those of the authors and do not necessarily represent the
official position of the Centers for Disease Control and Prevention.
ACIP Members
Wilbur Chen (Chair)
Kathy Poehling
Beth Bell
Veronica McNally
CDC Co -Leads
Gabriela Paz -Bailey
Laura Adams
Ex Officio Members
Kaitlyn Morabito (NIH)
Ralph LeBlanc (FDA)
Ihid Carneiro Leao (FDA)
Kirk Prutzman (FDA)
Srihari Seshadri  (DOD)
Liaison  Representatives
Elizabeth  Barnett  (AAP)
Rob Schechter  (AIM)Consultants
Edwin  Asturias
Robert  Atmar
Alan  Barrett
Iris Cardona
Anna  Durbin
Tony  Marfin
Kristen  Pierce
Anita  Shet
CDC Contributors
Joshua Wong
Nicole Medina
Mimi Eckert
Rachel Eidex
Alfonso Hernandez
Susan Hills
Terri Hyde
Mike McNeil
Jorge MunozErin Staples
Cindy Weinbaum
Rita Helfand
Non -Members
Mitchelle Flores -Febo
Parker Acevedo
Diana Duran
Angel RiveraQuestions?ACIP Dengue Vaccines Workgroup and Support Team

Summary: Update on Dengue Vaccines Joshua Wong, MD  Medical Officer | NCEZID/DVBD/Dengue Branch Meeting of the Advisory Committee on Immunization Practices June 26, 2024National Center for Emerging and Zoonotic Infections 1 Dengue Epidemiology Globally Countries reporting locally acquired dengue cases,  March 2023 –April 2024  Image from: https://www.ecdc.europa.eu/en/publications -data/countriesterritories -reporting -dengue -cases -march -2023 -and-april -2024 . Accessed 6/1/2024 Dengue cases in the…


01 COVID Daley 508

ACIP COVID -19 Vaccines Work Group
Dr. Matthew F. Daley, Work Group Chair
June 27, 2024National Center for Immunization and Respiratory Diseases

•ACIP met September 12, 2023 and recommended 2023 -2024 COVID -19 vaccines as authorized
under EUA or approved by BLA in persons aged ≥6 months
-Moderna COVID -19 vaccine in persons ≥6 months
-Pfizer -BioNTech COVID -19 vaccine in persons ≥6 months
-Novavax COVID -19 vaccine in persons ≥ 12 years*
•Everyone aged 5 years and older should get 1 dose of a 2023 -2024 COVID -19 vaccine to protect
against serious illness from COVID -19
•Children aged 6 months –4 years need multiple doses of COVID -19 vaccines to be up to date,
including at least 1 dose of 2023 -2024 COVID -19 vaccine
•People who are moderately or severely immune compromised may receive additional doses of
COVID -19 vaccines
•On February 28, 2024 ACIP recommended that adults ages 65 years and older receive one additional
2023 -2024 COVID -19 vaccine dose2023 -2024 COVID -19 vaccine recommendations
Abbreviations – EUA: Emergency Use Authorization, BLA: Biologics License Application
*People aged 12 years and older who have not previously received any COVID -19 vaccine doses and choose to get Novavax should get  2 doses of updated Novavax vaccine to be up to date.
•Reviewed evidence to inform recommendations for an additional dose of the 2023 -2024
COVID -19 vaccine for adults ages 65 years and older, including:
-COVID -19 hospitalizations
-COVID -19 vaccine coverage
-COVID -19 vaccine effectiveness
-Economic analysis of additional COVID -19 vaccine doses
-Evidence to Recommendations
•ACIP voted to recommend an additional dose of 2023 -2024 COVID -19 vaccine in persons ≥65
years
•Discussed next steps for the COVID -19 vaccine program, including shifting to a vote at the June
ACIP meeting for future vaccine updatesFebruary 2024 ACIP Meeting Review
•Framing of the policy question for the 2024 -2025 vaccine
-Started with considerations for universal v. risk -based recommendations
•Reviewed international COVID -19 vaccination policies from countries with
risk-based and age -based recommendations
•Discussed complexity of a risk -based recommendation, including
–Defining risk groups for severe outcomes
–Whether to take into account high risk of exposure
–Recommendations for persons not meeting risk criteria, including
those not previously vaccinated
•Discussed i mplementation challenges of non -universal policy options
-Work Group consensus was to proceed with deliberations for a universal
recommendation for everyone ages ≥ 6 months for 2024 -2025 vaccineACIP COVID -19 Work Group Meeting Review –
Initial planning
•Framing of the policy question for the 2024 -2025 vaccine
•Updated data on COVID -19 epidemiology, including risk factors for hospitalization due to
COVID -19 and epidemiology of Multisystem Inflammatory Syndrome in Children (MIS -C) and
Post -COVID Conditions
•Vaccine effectiveness of the 2023 -2024 COVID -19 vaccine
•Review of COVID -19 vaccine safety including longer -term outcomes of myocarditis
•Economic analysis of COVID -19 vaccination
•COVID -19 vaccine program implementation considerations
•Evidence to Recommendations Framework ACIP COVID -19 Work Group Meeting Review
March – June 2024
•June 5, 2024: FDA’s Vaccines and Related Biological Products Advisory
Committee (VRBPAC) met to discuss strain selection for 2024 -2025 COVID -
19 vaccines
-Based on the totality of the evidence presented, FDA advised
manufacturers to develop monovalent JN.1 lineage COVID -19 vaccines,
with a preference for the KP .2 strain, if feasible
-Anticipated 2024 -2025 vaccine doses will be broadly available in the fallCOVID-19 vaccine 2024-2025 Formula: VRBPAC Meeting
https://www.fda.gov/vaccines -blood -biologics/updated -covid -19-vaccines -use-united -states -beginning -fall-2024
COVID -19-associated hospitalizations
COVID-19 vaccine effectiveness update
Vaccine safety update for 2023-2024 COVID-19 vaccine
Economic analysis of COVID-19 vaccination
Evidence to recommendations
COVID-19 vaccine implementation   Dr. Fiona Havers
  Dr. Ruth Link -Gelles
Dr. Jonathan Duffy
 Dr. Lisa Prosser
  Dr. Lakshmi Panagiotakopoulos
  Dr. Shannon Stokely
Vote: 2024 -2025 COVID -19 vaccines in persons ages 6 months and olderAgenda: June 27, 2024
Work Group members
ACIP members
•Matthew Daley (chair)
•Oliver Brooks
•Robert Schechter
•Keipp Talbot
Ex-officio/government members
•BARDA: Christine Oshansky
•CDC: Alan Lam
•FDA: Rachel Zhang, Adam Spanier
•IHS: Uzo Chukwuma
•NIH: Chris Roberts
CDC co -Leads
•Megan Wallace
•Lakshmi PanagiotakopoulosLiaisons
•AAFP: Jonathan Temte
•AAP: Sean O’Leary
•ACOG: Naima Joseph (primary),
Laura Riley (alternate)
•ACP: Jason Goldman
•AGS: Ken Schmader
•AIM: Heather Roth
•AMA: Sandra Fryhofer
•ANA: Ruth Francis
•APhA : Richard Dang
•ASTHO: Marcus Plescia
•CSTE: Paul Cieslak, Christine Hahn
•IDSA: Jeff Duchin Liaisons, cont’d
•NACCHO: Matt Zahn (primary),
Jeff Duchin (alternate)
•NACI: Eva Wong (primary),
Matthew Tunis (alternate)
•NFID: Robert Hopkins (primary),
Bill Schaffner (alternate)
•SHEA: Preeti Mehrotra (primary),
Marci Drees (alternate)

Consultants
•Beth Bell
•Ed Belongia
•Hank Bernstein
•Kathy Edwards
•Lisa Jackson
•Kathy Kinlaw•Grace Lee
•Dayna Matthew
•Jennifer Nelson
•Stanley Perlman
•Peter Szilagyi
CDC participants
•Sarah Meyer
•Elisha Hall
•Danielle Moulia
•Monica Godfrey
•Hannah Rosenblum
•Katherine Fleming -Dutra
•Ruth Link -Gelles
•Lauren Roper
•Mary Chamberland
•Susan Goldstein
•Stephen Hadler
•JoEllen Wolicki
•Melinda Wharton
•Jessica MacNeil
•Latifa Boyce
•Amadea Britton
•Karen Broder•Carolyn Bridges
•Allison Ciesla
•Nicole Dowling
•Daniel Drapeau
•Kristen Folsom
•Ashley Fowlkes
•Jarrett Gartin
•Julianne Gee
•Samuel Graitcer
•Elizabeth Greene
•Lisa Grohskopf
•Aron Hall
•Demorah Hayes
•Rita Helfand
•Michele Hlavsa
•Terri Hyde
•Jefferson Jones
 •Andrew Kroger
•Josephine Mak
•Lauri Markowitz
•Michael McNeil
•Michael Melgar
•Noelle -Angelique Molinari
•Morgan Najdowski
•Kristen Nordlund
•Ismael Ortega -Sanchez
•Manisha Patel
•Pragna Patel
•Amanda Payne
•Georgina Peacock
•Jamison Pike
•Derrell Powers
•Sierra Scarbrough
•Jordan Singleton•Laura Steinhardt
•John Su
•Natalie Thornburg
•Evelyn Twentyman
•David Wentworth
•Dennis Wang
•Raigan Wheeler
•Ryan Wiegand
•Trang Wisard
•Patricia Yu
•Yon Yu
For more information, contact CDC
1-800-CDC-INFO (232- 4636)
TTY:  1- 888- 232-6348    cdc.gov
The findings and conclusions in this report are those of the authors and do not necessarily represent the official
position of the U.S. Centers for Disease Control and Prevention.

Summary: ACIP COVID -19 Vaccines Work Group Dr. Matthew F. Daley, Work Group Chair June 27, 2024National Center for Immunization and Respiratory Diseases  •ACIP met September 12, 2023 and recommended 2023 -2024 COVID -19 vaccines as authorized  under EUA or approved by BLA in persons aged ≥6 months -Moderna COVID -19 vaccine in persons ≥6 months  -Pfizer -BioNTech COVID -19 vaccine in persons ≥6 months  -Novavax COVID -19 vaccine in persons ≥ 12 years* •Everyone aged 5 years and older should get 1…


02 COVID Havers 508

Centers for Disease Control and Prevention
National Center for Immunization and Respiratory Diseases
Photographs and images included in this presentation are licensed solely for CDC/NCIRD online and presentation
use. No rights are implied or extended for use in printing or any use by other CDC CIOs or any external audiences.
COVID -19–Associated Hospitalizations among
Children and Adults — COVID -NET
ACIP Meeting
Fiona P . Havers, MD, MHS
RESP -NET Hospitalization Surveillance Team
Surveillance and Prevention Branch
Coronavirus and Other Respiratory Viruses Division
▪RESP -NET: COVID -NET, RSV -NET, FluSurv -NET
▪>300 acute -care hospitals
▪98 counties in 13 states
▪In 9 of 10 HHS regions
▪~10% of U.S. population
▪Positive SARS -CoV-2 within 14 days of or
during hospitalization
▪Screening or clinician -driven testing
▪Clinical data: representative sample of
COVID -NET patientsCOVID -NET: A RESP -NET population -based hospitalization
surveillance platform

Population -Based Rates of COVID -19-Associated
Hospitalizations — COVID -NET, March 2020 –May 2024
020406080100120140160
3/7/2020
5/7/2020
7/7/2020
9/7/2020
11/7/2020
1/7/2021
3/7/2021
5/7/2021
7/7/2021
9/7/2021
11/7/2021
1/7/2022
3/7/2022
5/7/2022
7/7/2022
9/7/2022
11/7/2022
1/7/2023
3/7/2023
5/7/2023
7/7/2023
9/7/2023
11/7/2023
1/7/2024
3/7/2024
5/7/2024Rate per 100,000 population
Week Ending DateWeekly Rates: March 2020 –May 2024
<6 months 6 months –4 years 5–11 years 12–17 years
18–49 years 50–64 years 65–74 years ≥75 yearsRates highest in ≥75 years, followed by
infants <6 months and adults 65 –74 years01002003004005006007008009001000Rate per 100,000 populationCumulative Rates: Oct 2023 –May 2024
020406080100120140160180200
10/7/2023 11/7/2023 12/7/2023 1/7/2024 2/7/2024 3/7/2024 4/7/2024 5/7/2024COVID -19-Associated Hospitalization Rate
per 100,000 population
Week ending date
White, non-Hispanic Black, non-Hispanic
American Indian/Alaska Native, non-Hispanic Asian/Pacific Islander, non-Hispanic
HispanicAge -Adjusted Cumulative Rates of COVID -19-Associated Hospitalizations
by Race and Ethnicity, All Ages — COVID -NET, October 2023 –May 2024
Percent of Weekly Hospitalizations by Age Group —
COVID -NET, March 2020 –May 2024
0%10%20%30%40%50%60%70%80%90%100%
3/7/2020
4/11/2020
5/16/2020
6/20/2020
7/25/2020
8/29/2020
10/3/2020
11/7/2020
12/12/2020
1/16/2021
2/20/2021
3/27/2021
5/1/2021
6/5/2021
7/10/2021
8/14/2021
9/18/2021
10/23/2021
11/27/2021
1/1/2022
2/5/2022
3/12/2022
4/16/2022
5/21/2022
6/25/2022
7/30/2022
9/3/2022
10/8/2022
11/12/2022
12/17/2022
1/21/2023
2/25/2023
4/1/2023
5/6/2023
6/10/2023
7/15/2023
8/19/2023
9/23/2023
10/28/2023
12/2/2023
1/6/2024
2/10/2024
3/16/2024
4/20/2024Percent of COVID -19-associated hospitalizations
Week ending date
≤17 years 18–49 years 50–64 years 65–74 years 75–84 years ≥85 yearsDuring
October 2023 –
May 2024:
•≥65: 67%  of COVID -19
hospitalizations
•<65: 33%  of COVID -19
hospitalizations
•≥75: 46%  of COVID -19
hospitalizations
•≤17: 4% of COVID -19
hospitalizations
Epidemiology of COVID -19–associated
hospitalizations among infants, children
and adolescents
0102030405060708090100Rate per 100,000 population
Week Ending Date
<6 months 6 months –4 years 5–11 years 12–17 yearsPopulation -Based Rates of COVID -19-Associated
Hospitalizations among Children and Adolescents Ages
≤17 Years — COVID -NET, March 2020 –May 2024
050100150200250300350 Weekly Rates, March 2020 –May 2024 Cumulative Rates
October 2023 –May 2024
024681012Rate per 100,000 population
Week Ending Date
6 months –4 years 5–11 years 12–17 yearsPopulation -Based Rates of COVID -19-Associated
Hospitalizations among Children and Adolescents Ages
6 months –17 Years — COVID -NET, March 2020 –May 2024
0102030405060 Weekly Rates, March 2020 –May 2024 Cumulative Rates
October 2023 –May 2024
Underlying Medical Conditions among Infants and Children Ages ≤4
Years with COVID -19-associated Hospitalization, by Age Group —
COVID -NET, July 2023 –March 2024
051015202530354045
<6 months 6–<2 years 2–4 yearsWeighted % of hospitalizations
Asthma/Reactive airway disease Neurologic disorders Feeding tube dependence
Cardiovascular disease Obesity Immunocompromising condition
Chronic lung disease* Blood disorders Prematurity
Data are limited to hospitalizations where COVID -19 is a likely primary reason for admission.
* Not including not asthma or reactive airway disease. Among children <2 years old, chronic lung disease includes bronchopulm onary dysplasia and chronic lung disease of prematurity. •50% of infants,
children, and
adolescents ages ≤17
years with COVID -19-
associated
hospitalization have
no underlying
medical conditions .<6 months:
75% with no underlying
conditions6 months –<2 years:
58% with no underlying
conditions2–4 years:
36% with no underlying conditions
Percent of COVID -19-Associated Hospitalizations with Underlying Medical
Conditions among Children and Adolescents Ages 5 –17 Years with COVID -19-
associated Hospitalizations, by Age Group — COVID -NET, July 2023 –March 2024
47
303836
21191822
19
131517
1311
814
05101520253035404550
5–11 years 12–17 yearsWeighted % of hospitalizations
Asthma Neurologic disorders
Feeding tube dependence Cardiovascular disease
Obesity Immunocompromising condition
Chronic lung disease, not including asthma Blood disorders
Data are limited to hospitalizations where COVID -19 is a likely primary reason for admission.
Only the most common underlying conditions are presented.•50% of infants,
children, and
adolescents ages ≤17
years with COVID -19-
associated
hospitalization have
no underlying medical
conditions .
•Among COVID -19-
associated
hospitalizations,
children and
adolescents ages ≥5
years are more likely
to have underlying
medical conditions
relative to infants and
children ages ≤4 years.5–11 years:
20% with no underlying
conditions12–17 years:
22% with no underlying
conditions
Age categoryAmong all
hospitalized
children, % with
no underlying
conditionsAmong those
admitted to ICU, %
with no underlying
conditions
(n=363)
<6 months 75% 56%
6–23 months 58% 52%
2–4 years 32% 28%
5–11 years 16% 4%
12–17 years 18% 19%
Overall ≤17 Years 50% 40%Underlying Medical Conditions among Patients Admitted to ICU among
Children and Adolescents Ages ≤17 Years with COVID -19-associated
Hospitalization, July 2023 –March 2024
Among those with no
underlying conditions,
what % were admitted
to ICU?
(n=791)
18%
17%
20%
5%
28%
18%
Hospitalizations are limited to those with COVID -19 as a likely primary reason for admission.
Vaccination Status among Children and Adolescents Ages ≤17
Years with COVID -19-associated Hospitalizations, by Age Group
— COVID -NET, October 2023 –March 2024
No record of bivalent or 2023 –2024 vaccine dose : No recorded doses of COVID -19 bivalent or the 2023 -2024 vaccine dose since August 2022. Bivalent booster, but no 2023 –2024 vaccine
dose : Received COVID -19 bivalent booster vaccination but no record of receiving 2023 -2024 vaccine dose since August 2022. 2023–2024 vaccine dose: Received 2023 -2024 vaccine dose.
Persons with unknown vaccination status are excluded. Hospitalizations are limited to those with COVID -19 as the presenting complaint upon admission.86
80 79
917 18
63 3
0102030405060708090
6 months –4 years 5–11 years 12–17 yearsPercent of hospitalizations
No record of bivalent or 2023 –2024 vaccine dose
Bivalent booster, but no 2023 –2024 vaccine dose
2023 –2024 vaccine dose•5% of children and
adolescents ages
≤17 years with
COVID -19-
associated
hospitalizations
received a 2023 –
2024 vaccine dose.
Epidemiology of COVID -19–associated
hospitalizations among adults
Weekly Population -Based Rates of COVID -19-Associated
Hospitalizations among Adults Ages ≥18 Years — COVID -NET,
March 2020 –May 2024
020406080100120140160
3/7/2020 3/7/2021 3/7/2022 3/7/2023 3/7/2024Rate per 100,000 population
Week Ending Date
18–49 years 50–64 years 65–74 years ≥75 years020040060080010001200
10/7/2023
11/7/2023
12/7/2023
1/7/2024
2/7/2024
3/7/2024
4/7/2024
5/7/2024Rate per 100,000 populationWeekly Rates, March 2020 –May 2024 Cumulative Rates
October 2023 –May 2024
1521
1722
191824
1623
0510152025
Jan-Mar 2022 Apr-Jun 2022 Jul-Sep 2022 Oct-Dec 2022 Jan-Mar 2023 Apr-Jun 2023 Jul-Sep 2023 Oct-Dec 2023 Jan-Mar 2024Weighted % of COVID -19-Associated HospitalizationsPercent of COVID -19-associated hospitalizations admitted from a long -term care facility
among adults ages ≥65 years, by quarter — COVID -NET, January 2022 –March 2024During January 2022 –March 2024, 19% of COVID -19-associated hospitalizations
among adults ages ≥65 years were residents of a long -term care facility.
Cumulative In -Hospital Death Rate during COVID -19-Associated
Hospitalization per 100,000 Population by Age Group —
COVID -NET, October 2023 –March 2024
0.562762
010203040506070
18–49 years 50–64 years 65–74 years ≥75 yearsIn-hospital death rate per
100,000 population
Age group
18–49 years 50–64 years 65–74 years ≥75 years
3% 15% 32% 50%Weighted
percent of in -
hospital deaths
by age group
Vaccination Status among Adults Ages ≥18 Years with COVID -19-
associated Hospitalization, by Age Group — COVID -NET, October
2023 –March 2024
78
65
58
48
19293436
36816
0102030405060708090
18–49 years 50–64 years 65–74 years ≥75 yearsPercent of hospitalizations
No record of bivalent or 2023 –2024 vaccine dose
Bivalent booster, but no 2023 –2024 vaccine dose
2023 –2024 vaccine dose
No record of bivalent or 2023 –2024 vaccine dose : No recorded doses of COVID -19 bivalent or 2023 -2024 vaccine dose since August 2022. Bivalent booster, but no 2023 –2024 vaccine dose :
Received COVID -19 bivalent booster vaccination but no record of receiving 2023 –2024 vaccine dose since August 2022. 2023–2024 vaccine dose: Received 2023 -2024 vaccine dose. Persons
with unknown vaccination status are excluded. •11% of adults ages
≥18 years with
COVID -19-associated
hospitalizations
received a 2023 –
2024 vaccine dose.
•57% of COVID -19-
associated
hospitalizations
among adults ages
≥18 years had not
received a COVID -19
vaccine after August
2022.
Percent of COVID -19-associated Hospitalizations among Adults Ages ≥18 Years with
Underlying Medical Conditions, by Age Group, with Top 4 Categories Highlighted —
COVID -NET, July 2023 –March 2024
Condition 18–49 years 50–64 years 65–74 years ≥75 years
Chronic lung disease 26 41 51 40
Asthma 19 17 17 10
COPD/Bronchitis 4 19 30 19
Cardiovascular disease 26 56 65 72
CAD/CABG/MI 4 18 34 32
CHF/Cardiomyopathy 8 23 29 29
Stroke/TIA 5 18 13 20
Diabetes 19 41 40 34
Immunocompromising condition 12 22 22 11
Neurologic condition 23 32 29 46
Renal Disease 12 25 25 33
Severe obesity (BMI ≥40 kg/m²) 16 14 6 3
COPD: chronic obstructive pulmonary disease; CAD: coronary artery disease; CABG: coronary artery bypass graft; TIA: transient  ischemic attack
Pink cells indicate the 4 most common underlying medical conditions within each age group; dark pink cells indicate the most com mon condition.
We used 3 data sources to calculate COVID -19–associated
hospitalization rates by chronic condition and age group
Numerator
 Denominator
•COVID -19–Associated Hospitalization
Surveillance Network (COVID –NET)•Behavioral Risk Factor Surveillance
System (BRFSS)
•Census population counts
Prevalence of chronic conditions among hospitalized adults in COVID -NET,
adults in COVID -NET states, and adults in the United States aged ≥18 years, 2022
Data are preliminary and subject to change. Obesity is defined as BMI 30 –39 kg/m²; severe obesity is defined as BMI ≥40 kg/m². O nly includes community dwelling residents. Non -community
dwelling persons, including those who resided in a long -term care facility upon admission, are excluded. COVID -19-related admiss ions are those where the primary reason for admission is
COVID -19-related illness. Prevalence data from COVID -NET states and United states are obtain from the Behavioral Risk Factor Sur veillance System, 2022 data.
•Except for asthma and obesity,
unadjusted prevalence is higher
among hospitalized COVID -19
patients relative to the general
population
•In adjusted models, except for
obesity, all other 8 conditions
examined were found to increase
the risk for COVID -19-associated
hospitalization.
•Magnitude of increased risk
varied by condition and age
group.
•Age ≥75 remains a strong risk
factor for hospitalization even in
adjusted models
•Results are limited to community -
dwelling adultsUnadjusted prevalence (%)
with 95% confidence intervals
▪Rates of COVID -19-associated hospitalizations highest among those
≤4 years
▪Rates highest among infants ages <6 months who are not vaccine
eligible and require a different approach for prevention (e.g.,
maternal vaccination)
▪50% have no underlying medical conditions
•Among children with no underlying medical conditions, 18% were
admitted to the ICU
▪October 2023 –March 2024: 5% of hospitalized children 6 months –  ≤
17 years had received a 2023 –2024 vaccine prior to admissionSummary – Infants, Children, and Adolescents
▪2/3 of all COVID -19-associated hospitalizations among those aged
≥65 years
▪During October 2023 –March 2024, 11% of hospitalized adult patients
had received a 2023 –2024 vaccine dose prior to admission
▪Underlying conditions increase risk for hospitalization, but age
remains strongly associated with the risk for hospitalizationSummary – Adults
Coronavirus and Other Respiratory
Viruses Division
Chris Taylor
Huong Pham
Sarah Hamid
Gordana Derado
Megan Wallace
Lakshmi Panagiotakopoulos
Katherine Fleming -DutraOther CDC staff
Rebecca Woodruff
RESP -NET Site investigators and staffAcknowledgements
For more information, contact CDC
1-800 -CDC -INFO (232 -4636)
TTY:  1 -888 -232-6348    www.cdc.gov
The findings and conclusions in this report are those of the authors and do not necessarily represent the official
position of the Centers for Disease Control and Prevention.
Photographs and images included in this presentation are licensed solely for CDC/NCIRD online and presentation
use. No rights are implied or extended for use in printing or any use by other CDC CIOs or any external audiences.

Summary: Centers for Disease Control and Prevention National Center for Immunization and Respiratory Diseases Photographs and images included in this presentation are licensed solely for CDC/NCIRD online and presentation  use. No rights are implied or extended for use in printing or any use by other CDC CIOs or any external audiences. COVID -19–Associated Hospitalizations among  Children and Adults — COVID -NET ACIP Meeting Fiona P . Havers, MD, MHS RESP -NET Hospitalization Surveillance Team…


03 COVID Link Gelles 508

Effectiveness of COVID -19 (2023-2024 Formula)
vaccines
Ruth Link-Gelles, PhD, MPH
CDR, US Public Health Service
Vaccine Effectiveness Program Lead
Coronavirus and Other Respiratory Viruses Division
Centers for Disease Control and Prevention
June 27, 2024National Center for Immunization and Respiratory Diseases

•Vaccine effectiveness (VE) methods refresher
•Context for interpretation of COVID -19 VE
•COVID -19 VE in adults, by outcome and variant:
-Symptomatic SARS -CoV-2
-COVID -19-associated emergency department/urgent care (ED/UC) encounters
-COVID -19-associated hospitalizations, by immunocompromise status
-COVID -19-associated critical outcomes
•COVID -19 VE in young children and by age groupAgenda: effectiveness of
COVID-19 ( 2023 -2024  Formula) vaccines
Case ControlPerson with acute
respiratory illness
Pathogen test
(e.g., SARS-CoV-2, RSV, etc.)
Immunization
status
Observational effectiveness
measured in a test-negative design (TND) study
𝑂𝑑𝑑𝑠 𝑜𝑓 𝑖𝑚𝑚𝑢𝑛𝑖𝑧𝑎𝑡𝑖𝑜𝑛Effectiveness = 1 –  (odds ratio) x 100%    Odds ratio = 𝑐𝑎𝑠𝑒𝑠
𝑂𝑑𝑑𝑠 𝑜𝑓 𝑖𝑚𝑚𝑢𝑛𝑖𝑧𝑎𝑡𝑖𝑜𝑛 𝑐𝑜𝑛𝑡𝑟𝑜𝑙𝑠Key features of a TND
•Real -world circumstances
•Study start is symptomatic medical encounter
•Heterogenous study population,
often “all comers”
•Benefits
•Reduces bias from health -care seeking behavior by including cases and controls
who presented to care and received testing (usually at the same facility).
•Efficient use of resources → allows controls to be selected from same healthcare
system or testing location as cases.
•Considerations
•Dependent on sensitivity and specificity of diagnostic testing.
•Controls positive for another vaccine preventable disease can bias results.
Sensitivity analyses excluding influenza positive controls can be helpful in
assessing COVID -19 VE.Test-negative design methods
Vaccine effectiveness is a population level estimate.
Adapted from : https://www.who.int/news -room/feature -stories/detail/vaccine -efficacy -effectiveness -and-protection

01020304050Vaccinated with 2023 -24 COVID -19 vaccine (%)
Week end dateAll children
6m-17y
12-17y
5-11y
6m-4yPercent of adults and children who received 2023-24 COVID-19 vaccine
National Immunization Survey-Adult COVID Module (NIS-ACM) and -Child COVID Module (NIS-CCM)
September 2023-April 2024
COVID-19 Vaccination Coverage with 2023-24 Vaccine
Among Adults ≥18 Years, NIS -ACMCOVID-19 Vaccination Coverage with 2023-24 Vaccine
Among Children 6 Months-17 Years, NIS- CCM
01020304050Vaccinated with 2023 -24 COVID -19 vaccine (%)
Week end dateAll adults
18+
75+
65-74
50-64
40-49
30-39
18-29
https://www.cdc.gov/vaccines/imz -managers/coverage/covidvaxview/index.html
•High rates of SARS -CoV-2 infection -induced immunity by July – August 2023.*Context for interpreting COVID-19 VE across age groups
* Internal CDC data. Data on persons aged ≥16 years is from a longitudinal, national cohort of >35,000 blood donors.
Methods and prior data available at: https://covid.cdc.gov/covid -data -tracker/#nationwide -blood -donor -seroprevalence -202289%
89%
84%
72%16-29 years
30-49 years
50-64 years
≥65 years
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percent with infection -induced immunityPercent of persons with infection -induced immunity,
based on anti -nucleocapsid results from blood donors
VE findings should be interpreted as the incremental benefit provided by COVID-19 vaccination
in a population with a high prevalence of vaccine- and infection-induced immunity.
Measuring 2023 -2024 COVID-19 VE
Measure Definition Vaccinated
groupComparison group
Absolute VE Compares frequency of health
outcomes in vaccinated and
unvaccinated people Received
updated
(2023 -24)
doseReceived no COVID -19 vaccines ever
Relative VE Compares frequency of health
outcomes in people who received
one type of vaccine to people who
received a different vaccineReceived
updated
(2023 -24)
doseEligible for, but did not receive, an
updated (2023 -24) dose , but received
previous doses of COVID -19 vaccine
VE presented today Compares people who received
2023 -2024 COVID -19 vaccine to
people who did not, regardless of
past vaccinationReceived
updated
(2023 -24)
doseEligible for, but did not receive, an
updated (2023 -24) dose , regardless of
past vaccination history
Updates to COVID -19 VE against symptomatic infection:
Increasing Community Access to Testing (ICATT) programMMWR Morb  Mortal Wkly  Rep 2024;73:77 –83. DOI: http://dx.doi.org/10.15585/mmwr.mm7304a2

•Nationwide community -based pharmacy SARS -CoV-2 testing
•Self-reported COVID -19 vaccination history at time of registration for SARS -CoV-2 testing*
•Design: Test-negative analysis**
•Population: Adults ≥18 years with ≥1 COVID -like symptom and nucleic acid amplification testing
(NAAT) for SARS -CoV-2
•Exclusion criteria: Individuals with self -reported immunocompromising conditions, reported a
positive SARS -CoV-2 test in preceding 90 days***
•Periods for analysis:
•Full analysis included tests from September 21, 2023 – May 22, 2024
•Sub-analysis using S -gene target failure**** included tests from October 27, 2023 – April 3, 2024Increasing Community Access to Testing (ICATT):
COVID-19 VE from national pharmacy testing data
*At 5% of testing encounters, COVID -19 vaccination status is collected by clinician interview. Receipt of 2023 -2024 COVID -19 vac cine formulation determined by date of most recent dose (i.e., after Sept 12, 2023).
**Odds ratios were calculated using multivariable logistic regression, adjusting for single year of age, gender, race/ethnici ty, SVI of the testing location (<0.5 versus ≥0.5), pharmacy contractor, underlying conditions (presence versus
absence), U.S. Department of Health and Human Services region of testing location, and date of testing
***Additional exclusion criteria: 1) reported receiving Novavax as their most recent dose and reported receiving <2 total COV ID-19 vaccine doses; 2) reported receiving a Janssen (Johnson & Johnson) COVID -19 vaccine dose after May
12, 2023; 3) received most recent COVID -19 dose <7 days prior to the date of testing or during September 1 -12, 2023; or 4) regis tered for testing with a version of the questionnaire that only reported month and year of the most
recent vaccine dose rather than calendar date.
**** Results of spike gene (S -gene) amplification in real -time reverse transcription –polymerase chain reaction (RT -PCR) can be u sed to distinguish certain SARS -CoV-2 lineages over time (2). S -gene target presence (SGTP) was detected
in most lineages that circulated in 2023, including XBB lineages, whereas S -gene target failure (SGTF) is detected in JN.1 and o ther BA.2.86 lineages
Link-Gelles, et al. MMWR 2024: http://dx.doi.org/10.15585/mmwr.mm7304a2  (Results updated with additional data since publication.)
Age group/2023 -2024 COVID -19 vaccination status/days since
doseTotal
testsSARS -CoV -2-
test -positive, N (%)Median interval since last dose
among those vaccinated, days
(IQR) Adjusted VE (95% CI)
≥18 years
No 2023 -2024 COVID -19 dose (ref) 12,965 4,661 (36) 687 (436 to 879) Ref
2023 -2024 COVID -19 dose , ≥7 days 1,895 483 (25) 70 (38 to 102) 45 (39 to 51)
2023 -2024 COVID -19 dose , 7-59 days earlier 772 181 (23) 32 (20 to 46) 53 (44 to 61)
2023 -2024 COVID -19 dose , 60-119 days earlier 809 237 (29) 84 (71 to 97) 34 (22 to 44)
2023 -2024 COVID -19 dose , 120 -179 days earlier 262 60 (23) 140 (128 to 152) 47 (28 to 60)
18-49 years
No 2023 -2024 COVID -19 dose (ref) 10,395 3,609 (35) 702 (451 to 887) Ref
2023 -2024 COVID -19 dose , ≥7 days 1,167 272 (23) 69 (39 to 101) 47 (38 to 54)
2023 -2024 COVID -19 dose , 7-59 days earlier 474 96 (20) 32 (19 to 46) 57 (46 to 66)
2023 -2024 COVID -19 dose , 60-119 days earlier 507 144 (28) 82 (71 to 95) 31 (15 to 43)
2023 -2024 COVID -19 dose , 120 -179 days earlier 147 27 (18) 139 (128 to 154) 56 (33 to 72)
≥50 years
No 2023 -2024 COVID -19 dose (ref) 2,570 1,052 (41) 610 (407 to 821) Ref
2023 -2024 COVID -19 dose , ≥7 days 728 211 (29) 71 (36 to 103) 40 (27 to 50)
2023 -2024 COVID -19 dose , 7-59 days earlier 298 85 (29) 32 (21 to 44) 44 (26 to 58)
2023 -2024 COVID -19 dose , 60-119 days earlier 302 93 (31) 85 (73 to 98) 35 (15 to 51)
2023 -2024 COVID -19 dose , 120 -179 days earlier 115 33 (29) 142 (128 to 152) 30 (-9 to 55)*
-20 0 20 40 60 80 100ICATT: VE of 2023-2024 COVID-19 vaccine against symptomatic infection
among adults aged ≥18 years, by age group and time since dose
September 2023 – May 2024
Link-Gelles, et al. MMWR 2024: http://dx.doi.org/10.15585/mmwr.mm7304a2  (Results updated with additional data since publication.)
*Some estimates are imprecise, which might be due to a relatively small number of persons in each level of vaccination or cas e status. This imprecision indicates that the actual VE could
be substantially different from the point estimate shown, and estimates should therefore be interpreted with caution. Additio nal data accrual could increase precision and allow more
precise interpretation. Ref=referent group; IQR=interquartile range; CI=confidence interval
Trends in estimated proportions of SARS -CoV-2 S-gene target presence
and variant proportions in ICATT and Nowcast projections from national
genomic surveillance
September 2023-April 2024
S-gene = spike gene; SGTF = S -gene target failure; SGTP = S -gene target presence
https://covid.cdc.gov/covid -data -tracker/#variant -proportions
Other
BA.2.86
JN.1
JN.1.13
HK.3
HV.1FL.1.5.1
SGT status/2023 -2024 COVID -19 vaccination status/days
since doseTotal
testsSARS -CoV -2 negative SARS -CoV -2 positive
Adjusted VE (95% CI) N (row %)Median interval
since last dose
among vaccinated,
days (IQR) N (row %)Median interval
since last dose
among vaccinated,
days (IQR)
SGT presence (likely non -JN.1)
No 2023 -2024 COVID -19 dose (ref) 2,357 1,934 (69) 668 (410 to 827) 423 (15) 670 (405 to 800) Ref
2023 -2024 COVID -19 dose , 60-119 days earlier 307 282 (77) 85 (72 to 101) 25 (7) 73 (69 to 83) 58 (33 to 73)
SGT failure (likely JN.1)
No 2023 -2024 COVID -19 dose (ref) 2,366 1,934 (69) 668 (410 to 827) 432 (15) 686 (426 to 829) Ref
2023 -2024 COVID -19 dose , 60-119 days earlier 343 282 (77) 85 (72 to 101) 61 (17) 89 (75 to 101) 37 (13 to 51)
0 20 40 60 80 100ICATT: VE of 2023-2024 COVID-19 vaccine against symptomatic infection
among adults aged ≥18 years, by S -gene target (SGT) presence or failure and
time since dose
October 2023 – April 2024
Link-Gelles, et al. MMWR 2024: http://dx.doi.org/10.15585/mmwr.mm7304a2  (Results updated with additional data since publication.)
Updates to COVID -19 VE against COVID- 19-associated
ED/UC encounters :
VISION and IVY NetworksMMWR Morb  Mortal Wkly  Rep 2024;73:180 –188. DOI: http://dx.doi.org/10.15585/mmwr.mm7308a5

VISION Multi -Site Network of Electronic Health Records
369 emergency rooms and urgent cares/229 hospitals
▪Design: Test-negative analysis
▪Population: Adults visiting a participating
emergency department or urgent care (ED/UC) or
hospitalized with COVID -19-like illness (CLI) with a
SARS -CoV-2 NAAT test result within 10 days before
or 72 hours after encounter
−Cases : CLI with positive  NAAT for SARS -CoV-2 and no
positive NAAT for RSV or influenza
–Controls : CLI with negative  NAAT for SARS -CoV-2 and
no positive NAAT for influenza
▪Vaccination data: Documented by electronic health records and state and
city registries
Age group/2023 -2024 COVID -19 vaccination status/days since
doseTotal
encountersSARS -CoV -2-
test -positive,
N (%)Median interval
since last dose among
vaccinated among those
vaccinated, days (IQR) Adjusted VE (95% CI)
≥18 years
No 2023 -2024 COVID -19 dose (ref) 207,695 22,530 (11) 720 (481 -865) Ref
2023 -2024 COVID -19 dose , ≥7 days 37,809 2,720 (7) 82 (46 -123) 36 (33 -39)
2023 -2024 COVID -19 dose , 7-59 days earlier 13,144 982 (7) 34 (21 -47) 50 (46 -53)
2023 -2024 COVID -19 dose , 60-119 days earlier 14,434 1,171 (8) 87 (73 -103) 32 (27 -36)
2023 -2024 COVID -19 dose , 120 -179 days earlier 10,231 567 (6) 146 (132 -161) 1 (-9-9)
18-64 years
No 2023 -2024 COVID -19 dose (ref) 148,273 15,100 (10) 751 (573 -887) Ref
2023 -2024 COVID -19 dose , ≥7 days 13,696 819 (6) 78 (42 -119) 38 (33 -43)
2023 -2024 COVID -19 dose , 7-59 days earlier 5,137 313 (6) 34 (20 -47) 53 (47 -58)
2023 -2024 COVID -19 dose , 60-119 days earlier 5,186 345 (7) 87 (73 -103) 33 (25 -40)
2023 -2024 COVID -19 dose , 120 -179 days earlier 3,373 161 (5) 144 (131 -159) -3 (-21-13)
≥65 years
No 2023 -2024 COVID -19 dose (ref) 59,422 7,430 (13) 609 (399 -803) Ref
2023 -2024 COVID -19 dose , ≥7 days 24,113 1,901 (8) 84 (47 -126) 35 (31 -38)
2023 -2024 COVID -19 dose , 7-59 days earlier 8,007 669 (8) 35 (21 -47) 47 (42 -51)
2023 -2024 COVID -19 dose , 60-119 days earlier 9,248 826 (9) 88 (73 -103) 32 (26 -37)
2023 -2024 COVID -19 dose , 120 -179 days earlier 6,858 406 (6) 146 (133 -162) 7 (-5-17)VISION: VE of 2023-2024 COVID-19 vaccine against ED/UC encounters among
immunocompetent adults aged ≥18 years, by age group
September 2023 – May 2024
*Some estimates are imprecise, which might be due to a relatively small number of persons in each level of vaccination or case  status. This imprecision indicates that the actual VE could be substantially different
from the point estimate shown, and estimates should therefore be interpreted with caution. Additional data accrual could incr ease precision and allow more precise interpretation.
https://www.cdc.gov/mmwr/volumes/73/wr/mm7308a5.htm  (Results updated with additional data since publication.) VE was calculated as (1 − odds ratio) x 100%, estimated using a tes t-negative case -control
design, with the odds ratio adjusted for age, sex, race and ethnicity, geographic region, and calendar time. -40 -20 0 20 40 60 80 100
Updates to COVID -19 VE against COVID-19-associated
hospitalization and critical illness:
VISION and IVY NetworksMMWR Morb  Mortal Wkly  Rep 2024;73:180 –188. DOI: http://dx.doi.org/10.15585/mmwr.mm7308a5

VISION: VE of 2023-2024 COVID-19 vaccine against hospitalization among
immunocompetent adults aged ≥18 years, by age group
September 2023 – May 2024
Age group/2023 -2024 COVID -19 vaccination status/days
since doseTotal
encountersSARS -CoV -2-
test -positive,  N (%)Median interval since last dose
among those vaccinated,
days (IQR) Adjusted VE (95% CI)
≥18 years
No 2023 -2024 COVID -19 dose (ref) 63,908 6,484 (10) 693 (448 -852) Ref
2023 -2024 COVID -19 dose , ≥7 days 13,195 912 (7) 84 (46 -127) 41 (37 -46)
2023 -2024 COVID -19 dose , 7-59 days earlier 4,458 345 (8) 34 (20 -47) 49 (43 -55)
2023 -2024 COVID -19 dose , 60-119 days earlier 4,928 362 (7) 88 (73 -104) 43 (36 -49)
2023 -2024 COVID -19 dose , 120 -179 days earlier 3,809 205 (5) 146 (133 -162) 14 (0 -27)
18-64 years
No 2023 -2024 COVID -19 dose (ref) 25,209 1,644 (7) 743 (544 -888) Ref
2023 -2024 COVID -19 dose , ≥7 days 2,363 114 (5) 80 (42 -121) 30 (14 -42)
2023 -2024 COVID -19 dose , 7-59 days earlier 870 52 (6) 33 (20 -45) 29 (5 -47)
2023 -2024 COVID -19 dose , 60-119 days earlier 887 43 (5) 88 (74 -103) 35 (11 -53)
2023 -2024 COVID -19 dose , 120 -179 days earlier 606 19 (3) 146 (134 -160) 15 ( -37-47)*
≥65 years
No 2023 -2024 COVID -19 dose (ref) 38,699 4,840 (13) 651 (419 -827) Ref
2023 -2024 COVID -19 dose , ≥7 days 10,832 798 (7) 85 (47 -128) 42 (37 -47)
2023 -2024 COVID -19 dose , 7-59 days earlier 3,588 293 (8) 34 (20 -47) 52 (46 -58)
2023 -2024 COVID -19 dose , 60-119 days earlier 4,041 319 (8) 88 (73 -104) 43 (35 -49)
2023 -2024 COVID -19 dose , 120 -179 days earlier 3,203 186 (6) 147 (133 -162) 13 ( -2-26)
-40 -20 0 20 40 60 80 100*Some estimates are imprecise, which might be due to a relatively small number of persons in each level of vaccination or case  status. This imprecision indicates that the actual VE could be substantially different
from the point estimate shown, and estimates should therefore be interpreted with caution. Additional data accrual could incr ease precision and allow more precise interpretation.
https://www.cdc.gov/mmwr/volumes/73/wr/mm7308a5.htm  (Results updated with additional data since publication.) VE was calculated as (1 − odds ratio) x 100%, estimated using a tes t-negative case -control
design, adjusted for age, sex, race and ethnicity, geographic region, and calendar time.
VISION: VE of 2023-2024 COVID-19 vaccine against hospitalization among
adults aged ≥18 years, by immunocompromise status
September 2023 – May 2024
Immunocompromise status/2023 -2024 COVID -19 vaccination
status/days since doseTotal
encountersSARS -CoV -2-
test -positive
 N (%)Median interval since
last dose among those
vaccinated, days (IQR) Adjusted VE (95% CI)
≥18 years, non -immunocompromised
No 2023 -2024 COVID -19 dose (ref) 63,908 6,484 (10) 693 (448 -852) Ref
2023 -2024 COVID -19 dose , ≥7 days 13,195 912 (7) 84 (46 -127) 41 (37 -46)
2023 -2024 COVID -19 dose , 7-59 days earlier 4,458 345 (8) 34 (20 -47) 49 (43 -55)
2023 -2024 COVID -19 dose , 60-119 days earlier 4,928 362 (7) 88 (73 -104) 43 (36 -49)
2023 -2024 COVID -19 dose , 120 -179 days earlier 3,809 205 (5) 146 (133 -162) 14 (0 -27)
≥18 years, immunocompromised
No 2023 -2024 COVID -19 dose (ref) 17,574 1,463 (8) 644 (414 -826) Ref
2023 -2024 COVID -19 dose , ≥7 days 4,673 289 (6) 84 (46 -127) 28 (18 -38)
2023 -2024 COVID -19 dose , 7-59 days earlier 1,573 104 (7) 34 (21 -46) 39 (25 -51)
2023 -2024 COVID -19 dose , 60-119 days earlier 1,753 123 (7) 88 (74 -105) 27 (10 -40)
2023 -2024 COVID -19 dose , 120 -179 days earlier 1,347 62 (5) 146 (133 -162) 3 (-29-27)*
-60 -40 -20 0 20 40 60 80 100
Additional methods, including definition of immunocompromised available: https://www.cdc.gov/mmwr/volumes/73/wr/mm7308a5.htm  (Results updated with additional data since publication.) VE
was calculated as (1 − odds ratio) x 100%, estimated using a test -negative case -control design, adjusted for age, sex, race and ethnicity, geographic region, and calendar time.
* Some estimates are imprecise, which might be due to a relatively small number of persons in each level of vaccination or ca se status. This imprecision indicates that the actual VE could be
substantially different from the point estimate shown, and estimates should therefore be interpreted with caution. Additional  data accrual could increase precision and allow more precise
interpretation.
VISION: VE of 2023-2024 COVID-19 vaccine against critical illness among
immunocompetent adults aged ≥18 years, by age group
September 2023 – May 2024
Age group/2023 -2024 COVID -19 vaccination status/days since
doseTotal
encountersSARS -CoV -2-
test -positive
 N (%)Median interval
since last dose among
those vaccinated,
days (IQR) Adjusted VE (95% CI)
≥18 years
No 2023 -2024 COVID -19 dose (ref) 58,576 1,152 (2) 694 (452 -855) Ref
2023 -2024 COVID -19 dose , ≥7 days 12,402 119 (1) 85 (46 -128) 58 (49 -66)
2023 -2024 COVID -19 dose , 7-59 days earlier 4,151 38 (1) 34 (21 -47) 69 (57 -78)
2023 -2024 COVID -19 dose , 60-119 days earlier 4,616 50 (1) 88 (74 -104) 57 (43 -68)
2023 -2024 COVID -19 dose , 120 -179 days earlier 3,635 31 (1) 147 (133 -162) 32 (0 -53)*
0 20 40 60 80 100
CDC unpublished data. Critical illness defined as admission to an intensive care unit (ICU) or death while hospitalized or ≤2 8 days after hospital admission. VE was calculated as (1 − odds ratio) x 100%,
estimated using a test -negative case -control design, adjusted for age, sex, race and ethnicity, geographic region, and calendar time.
*Some estimates are imprecise, which might be due to a relatively small number of persons in each level of vaccination or cas e status. This imprecision indicates that the actual VE could be
substantially different from the point estimate shown, and estimates should therefore be interpreted with caution. Additional  data accrual could increase precision and allow more precise
interpretation.
IVY Network —26 hospitals, 20 U.S. States
•Design : Test-negative, case -control design
•Population : Adults  aged  ≥18 years  hospitalized with COVID -
like illness (CLI)* and SARS -CoV-2 test results within 10 days of
illness onset and 3 days of admission
–Cases: CLI and test  positive  for SARS -CoV-2 by NAAT or antigen
–Co-infections with influenza and RSV are excluded
–Controls : CLI and test negative  for SARS -CoV-2 and influenza by
RT-PCR
•Vaccination data: Electronic medical records (EMR), state and
city registries, and plausible self -report
•Specimens: Nasal swabs  obtained on all patients for central
RT-PCR testing and whole genome sequencing
*CLI is defined as presence of any one of the following: fever, cough, shortness of breath, chest imaging consistent with pneumoni a, or hypoxemia

IVY: VE of 2023–2024 vaccine against hospitalization among immuno competent
adults aged ≥18 years, by age group and time since dose
September 21, 2023 – April 30, 2024
*Logistic regression models were adjusted for age, sex, race and ethnicity, geographic region, and calendar time.COVID -19 dosage pattern/age groupCOVID -19
case -patients
N (Col %)COVID -19
control -
patients
N (Col %)Median interval
since last dose among
those vaccinated,
days (IQR)VE*
% (95% CI)
≥18 years
No 2023 -2024 COVID -19 dose (ref) 1538 (89) 4149 (84) 681 (430 –840) Ref
2023 -2024 COVID -19 dose , ≥7 days 191 (11) 786 (16) 81 (43 –121) 37 (24 –47)
2023 -2024 COVID -19 dose , 7–89 days earlier 110 (6) 441 (9) 48 (26 -69) 41 (26 –53)
2023 -2024 COVID -19 dose , 90–179 days earlier 81 (5) 345 (7) 127 (107 –148) 27 (4 –44)
18–64 years
No 2023 -2024 COVID -19 dose (ref) 530 (95) 2084 (90) 733 (485 –879) Ref
2023 -2024 COVID -19 dose , ≥7 days 27 (5) 236 (10) 73 (34 –112) 52 (26 –68)
≥65 years
No 2023 -2024 COVID -19 dose (ref) 1008 (86) 2065 (79) 643 (406 –802) Ref
2023 -2024 COVID -19 dose , ≥7 days 164 (14) 550 (21) 82 (45 –123) 35 (20 –47)
0 20 40 60 80 100
Vaccine  Effectiveness (%)
IVY*: VE of 2023–2024 vaccine against hospitalization among adults aged
≥18 years by SARS -CoV-2 lineage using viral whole -genome sequencing
•Population
•Cases:  COVID -like illness (CLI) and test positive for SARS -CoV-2†;restricted to patients with sequence -
confirmed§JN lineage (BA.2.86 and its descendants)  infection or XBB lineage (all other co -circulating
lineages) infections
•Controls: CLI and test negative forSARS -CoV-2 and influenza viruses by RT-PCR
•Analytic Period: October 18, 2023 –March 9, 2024
•First date on which a patient was admitted with sequence -confirmed JN lineage infection
•Last week during which a patient was admitted with sequence -confirmed XBB lineage infection
•VE¶ against hospitalization was calculated separately using case -patients with sequence -confirmed SARS -
CoV-2 JN and XBB lineage infections
* Investigating Respiratory Viruses in the Acutely Ill (IVY) Network. https://www.cdc.gov/flu/vaccines -work/ivy.htm
† Case patients who tested positive for influenza viruses or RSV were excluded.
§ Identification of a SARS -CoV-2 lineage through viral whole -genome sequencing was successful for 63% of case -patients during the  analysis period.
¶ Odds ratios were adjusted for age, sex, race and ethnicity, geographic region, calendar time, and Charlson comorbidity index.
IVY: Number of COVID -19 case -patients by hospital admission week and SARS -
CoV-2 lineage
October 18, 2023 – March 9, 2024
* Dates are for the end of the admission week.
† JN lineages comprised BA.2.86 and its descendants. XBB lineages comprised all other co -circulating lineages.
Identification of a SARS -CoV-2 lineage through viral whole -genome sequencing was successful for 63% of case -patients during the analysis period.†
COVID -19 dosage patternCOVID -19 control -patients COVID -19 case -patients
VE** (95% CI) N (Col %)Median interval
since last dose
among vaccinated,
days (IQR)  N (Col %)Median interval
since last dose
among vaccinated,
days (IQR)
XBB lineages†
No 2023 -2024 COVID -19 dose (ref) 3736 (82) 688 (429 –834) 532 (91) 557 (385 –751) Ref
2023 -2024 COVID -19 dose , 7–89 days earlier 568 (12) 47 (26 –68) 47 (8) 44 (22 –67) 54 (36 –67)
2023 -2024 COVID -19 dose , 90–179 days earlier 276 (6) 118 (106 –131) 6 (1) 92 (91 –105) §
JN lineages†
No 2023 -2024 COVID -19 dose (ref) 3736 (82) 688 (429 –834) 319 (80) 746 (479 –855) Ref
2023 -2024 COVID -19 dose , 7–89 days earlier 568 (12) 47 (26 –68) 38 (10) 56 (31 –74) 33 (2 –54)¶
2023 -2024 COVID -19 dose , 90–179 days earlier 276 (6) 118 (106 –131) 40 (10) 118 (107 –130) 23 (-12 to 48)¶IVY: VE of 2023–2024 COVID -19 vaccine against hospitalization among
adults aged ≥18 years*, by SARS -CoV-2 lineage and time since dose
October 18, 2023 – March 9, 2024
CDC unpublished data.* These results include both immunocompetent and immunocompromised persons.
† JN lineages comprised BA.2.86 and its descendants. XBB lineages comprised all other co -circulating lineages.
§ Based on timing of recommendations to receive 2023 –2024 COVID -19 vaccines and JN lineage emergence, limited numbers of individu als with XBB infection
were 90–179 days from their updated dose, precluding estimation of VE within this stratum.
¶ Some estimates are imprecise, which might be due to a relatively small number of persons in each level of vaccination or case  status. This imprecision
indicates that the actual VE could be substantially different from the point estimate shown, and estimates should therefore be i nterpreted with caution.
** VE estimates adjusted for age, sex, race and ethnicity, geographic region, calendar time, and Charlson comorbidity index.-20 020406080100
Vaccine  Effectiveness (%)
COVID -19 VE in young children and
by age group
Reminder: children aged 6 months -4 years continue to
be recommended for a complete initial series

Age group | COVID -19 vaccination statusTotal
encountersSARS -CoV -2-
test -positive, N (%)Median interval since
last dose among
those vaccinated,
days (IQR) Adjusted VE (95% CI)
No updated 2023 -2024 COVID -19 vaccine dose*
9 months -4 years 30,286 1,180 (4) 349 (236 -443) Ref
5-17 years 37,203 1,449 (4) 650 (449 -769) Ref
18-64 years 148,273 15,100 (10) 751 (573 -887) Ref
≥65 years 59,422 7,430 (13) 609 (399 -803) Ref
2023 -2024 COVID -19 dose received 7 -59 days earlier
9 months -4 years 613 10 (2) 33 (19 -46) 66 (36 -82)
5-17 years 805 11 (1) 33 (19 -47) 71 (47 -84)
18-64 years 5,137 313 (6) 34 (20 -47) 53 (47 -58)
≥65 years 8,007 669 (8) 35 (21 -47) 47 (42 -51)
2023 -2024 COVID -19 dose received 60 -179 days earlier
9 months -4 years 706 14 (2) 104 (80 -137) 24 (-31-56)**
5-17 years 1,343 22 (2) 111 (86 -138) 50 (22 -68)
18-64 years 8,559 506 (6) 108 (82 -137) 24 (17 -31)
≥65 years 16,106 1,232 (8) 111 (84 -142) 25 (20 -30)VISION: VE of 2023–2024 COVID -19 vaccine doses against ED/UC encounters
was similar across age groups
September 2023 – May 2024
-80-60-40-20 020406080100
* Includes all individuals who did not receive a 2023 -2024 COVID -19 vaccine. For those aged ≥5 years, this includes unvaccinated  persons and persons who were vaccinated with ≥1 original
monovalent or bivalent COVID -19 doses. For those aged <5 years, both those in the referent group and those in the vaccinated gro up were required to have completed an initial series. The 2023 -
2024 dose could have been part of the initial series or in addition to the initial series.
** Some estimates are imprecise, which might be due to a relatively small number of persons in each level of vaccination or c ase status. This imprecision indicates that the actual VE could be
substantially different from the point estimate shown, and estimates should therefore be interpreted with caution. Additional  data accrual could increase precision and allow more precise
interpretation.
•2023 -2024 COVID -19 vaccination provided increased protection against symptomatic SARS -
CoV-2 infection and COVID -19-associated ED/UC visits and hospitalizations compared to no
2023 -2024 vaccine dose.
•Waning patterns appeared similar to previous COVID -19 vaccine formulations; most durable
protection appeared to be for critical illness, though statistical power was lacking in the
longest time period since vaccination
•As with previous COVID -19 vaccine formulations, effectiveness was similar across age groups
•Receipt of 2023 -2024 COVID -19 vaccine provided protection against JN.1 and other circulating
variants, though may be lower than protection provided against XBB sublineage variants Conclusions
Acknowledgements
CDC
Amadea Britton
Allison Ciesla
Fatimah Dawood
Jennifer DeCuir
Monica Dickerson
Katherine Fleming -Dutra
Sascha Ellington
Shikha Garg
Nathaniel M. Lewis
Kevin Ma
Josephine Mak
Joe Miller
Morgan Najdowski
Erica Okwuazi
Lakshmi Panagiotakopoulos
Zach Smith
Diya Surie
Caitlin Ray
Mark Tenforde
Megan Wallace
Ryan WiegandVISION Collaborators
Westat
Sarah Bell
Angela Cheung
Margaret Dunne
Patrick Mitchell
Sarah Reese
Elizabeth Rowley
Janet Watts
Zack Weber
Intermountain Health
Kristin Dascomb
Kaiser Permanente Center for Health Research
Stephanie A. Irving
Kaiser Permanente Northern California
Nicola P. Klein
Regenstrief
Shaun J. Grannis
University of Colorado
Toan C. Ong
HealthPartners
Malini B. DeSilva
Columbia University
Karthik Natarajan
+ many more site staff!IVY Collaborators
Cristie  Columbus
Laurence W. Busse
Steven Y . Chang
Abhijit Duggal
Matthew C. Exline
Manjusha Gaglani
Kevin W. Gibbs
Adit A. Ginde
David N. Hager
Estelle S. Harris
Cassandra Johnson
Nicholas J. Johnson
Akram Khan
Jennie H. Kwon
Adam S. LauringChristopher Mallow
Emily Martin
Amira Mohamed
Nicholas M. Mohr
Jarrod M. Mosier
Ithan  D. Peltan
Matthew Prekker
Basmah  Safdar
Wesley H. Self
Nathan I. Shapiro
Jay S. Steingrub
Ivana A. Vaughn
Jennifer G. Wilson
Yuwei Zhu

Summary: Effectiveness of COVID -19 (2023-2024 Formula)  vaccines  Ruth Link-Gelles, PhD, MPH CDR, US Public Health Service Vaccine Effectiveness Program Lead Coronavirus and Other Respiratory Viruses Division Centers for Disease Control and Prevention  June 27, 2024National Center for Immunization and Respiratory Diseases   •Vaccine effectiveness (VE) methods refresher •Context for interpretation of COVID -19 VE •COVID -19 VE in adults, by outcome and variant: -Symptomatic SARS -CoV-2 -COVID…


04 COVID Duffy 508

COVID -19 vaccine safety surveillance
for the 2023 -2024 season
Jonathan Duffy, MD, MPH
Immunization Safety Office
June 27, 2024National Center for Emerging and Zoonotic Infectious Diseases

•Vaccine Adverse Event Reporting System (VAERS)
•V-s afe
•Vaccine Safety Datalink (VSD)CDC surveillance systems monitoring COVID -19
vaccine safety
2
•The Vaccine Safety Datalink (VSD) identified two statistical signals for mRNA COVID- 1 9 vaccines
during the 2023 -2024 season
-Guillain -B arré syndrome (GBS) following Pfizer COVID -19 vaccine among people aged ≥65 years
•An association between mRNA COVID -19 v accines and GBS had not been observed prior to this season
in VSD or other systems
•The increased rate ratio observed during the 2023- 2024 season may or may not represent a true risk
•If ther e is a true risk, it is estimated to be similar to  what is considered acceptable for other adult
vaccines
-Ischemic stroke following Moderna (aged ≥65 years) and Pfizer (aged 50 -6 4 years) COVID -19 vaccines
•The VSD previously observed a statistical signal for ischemic stroke during 2022-2023 for bivalent
P
fizer COVID -19 vaccine (aged ≥65 years)
•Available data do not provide clear and consistent evidence of a safety problem for ischemic stroke wi
th mRNA COVID -19 vaccines
•No other new or unexpected safety concerns were identified for the 2023 -2024 C OVID -19 vaccines
•Any real or theoretical risks of vaccine adverse events need to be placed in the context of the
b
enefits of COVID- 19 vaccines in preventing COVID- 19 and its potentially serious complicationsKey points up front
3
Vaccine Adverse Event Reporting System
(VAERS)
5
VAERS: U.S. reports following COVID -19 vaccination1
Manufacturer Reports
NAge,
years
Median (IQR)Sex,
female
N (%)Non -serious
N (%)Serious2
N (%)Onset interval,
days
Median (IQR)
Pfizer 7,215 57 (33– 70) 4,129 (57) 6,781 (94) 434 (6) 0 (0–3)
Moderna 5,954 60 (31– 72) 3,474 (58) 5,502 (92) 457 (8) 0 (0–1)
Novavax 153 51 (35–70) 86 (56) 140 (92) 13 (8) 1 (0–2)
Unknown 176 58.5 ( 34–71) 95 (54) 152 (86) 24 (14) 0 (0–1)
Total 13,491 59 (32–71) 7,780 (58) 12,568 (93) 923 (7) 0 (0–2)
1. Reports received during September 12, 2023 – April 19, 2024; reported date of vaccination during September 12, 2023 –  April 1 9, 2024  or missing
2. Based on the U. S. Code of Federal Regulations (21 CFR 600.80), classification of a serious adverse event includes a repor t of one of the following:
death, life -threatening illness, hospitalization or prolongation of hospitalization, permanent disability, congenital anomaly, o r birth defect. 6
VAERS: most frequent MedDRA Preferred Terms
following COVID -19 vaccination by manufacturer
Pfizer Moderna Novavax
MedDRA PTN=7,215
n (%)MedDRA PTN=5,954
n (%)MedDRA PTN=153
n (%)
COVID -19 1899 (26) Fever 743 (13) Headache 21 (13)
Headache 485 (7) Fatigue 729 (12) Fever 19 (12)
Fatigue 465 (6) Headache 712 (12) Pain 18 (11)
Fever 407 (6) Pain 546  (9) Pain in extremity 18 (11)
Pain 365 (5) Pain in extremity 502 (8) Fatigue 15 (9)
Reports received during September 12, 2023 – April 19, 2024; reported date of vaccination during September 12, 2023 – April 19, 2024 or missing.
MedDRA PT = Medical Dictionary for Regulatory Activities Preferred Terms ( https://www.meddra.org ). More than one MedDRA Preferred Term may be
assigned to a single report.
Percents represent the number of reports divided by the total number of reports for each vaccine. 7
V-safe
•Participants self -e nroll at https://vsafe.cdc.gov
•Post -v accination surveys
-Daily during the first week
-Weekly through w eek 6
•Daily surveys solicit adverse events and health impacts after v accination
-Local  r eactions (e.g., pain, redness, swelling)
-Systemic reactions (e.g., fatigue, headache, muscle pain)
-Health impacts (e.g., unable to perform normal daily activities, missed school or
w
ork, or received medical care)V-safe methods
9
V-safe: characteristics of participants with reported
COVID -19 vaccination1
CharacteristicVaccine manufacturer, %
Moderna
N=4,828Pfizer
N=4,481Novavax
N=258Do not know
N=576Total
N=10,143
Female sex assigned at birth 61.5 61.2 69.4 63.7 61.7
Age group, years
 3-17 0.2 0.6 0.8 - 0.4
 18-59 26.5 30.8 41.9 34.6 29.3
 ≥60 73.3 68.6 57.4 65.5 70.4
Immunocompromised 7.7 7.0 8.5 5.0 7.2
Vaccine(s) co -administered 18.3 21.0 14.0 33.0 20.2
 Influenza 8.1 9.9 7.8 17.0 9.4
 RSV 3.5 3.5 2.3 4.9 3.5
 Other 6.7 7.6 3.9 11.1 7.3
1. For 10,143 V -safe participants aged ≥3 years enrolled in the COVID -19 protocol with ≥1 completed daily survey during Septembe r 11, 2023- May 27, 2024.
10
V-safe: percent of people aged ≥3 years who reported reactions and health
impacts at least once in days 0 -7 following COVID -19 vaccination,
by manufacturer
0.7 0.6 0.4 0.7
0102030405060708090100
Any symptoms Injection site
reactionSystemic reaction Unable to
complete daily
activitiesUnable to work or
attend schoolGot medical carePercent
Moderna Pfizer Novavax Don't know
11
Vaccine Safety Datalink
(VSD)
Vaccine Safety Datalink (VSD)
Collaborative
pr
oject between
CDC and 13 integrated healthcare organizations
Population of ~1
3.5 million
people annually
13
•Sequential monitoring as data become available
•Monitors a limited set of prespecified outcomes of special interest
•Designed to detect statistical signals (values above specified statistical
thresholds)
•Statistical signals are potential associations and f urther investigation is
required before concluding that a safety concern existsVSD Rapid Cycle Analysis (RCA) surveillance
14
•Time period:  September 10, 2023 – April 27, 2024
•Evaluated the first COVID -19 vaccine dose received during this period
•Design:  analysis using COVID -19 vaccinated concurrent comparators
-Compares the outcome incidence among vaccinees in a risk interval with
outcome incidence on the same day among vaccinees in a comparison interval
-Adjusted for outcome calendar date, age group, sex, race/ethnicity, VSD site
•Statistical signal criteria:
-The signal threshold is determined from an alpha- spending plan that keeps the
overall chance of a Type 1 error <0.05 during the surveillance period
-Supplemental rate ratios with exact 95% confidence intervals VSD RCA methods for the
2023 -2024 COVID -19 vaccine
15
VSD pre -specified outcomes
Acute disseminated encephalomyelitis (ADEM)
Acute myocardial infarction
Encephalitis / myelitis / encephalomyelitis
(not ADEM or TM)
Guillain -Barré syndrome (GBS)
Hemorrhagic stroke
Ischemic stroke
Immune thrombocytopenia
Myocarditis / pericarditis
Pulmonary embolism
Seizure
Transverse myelitis (TM)
16
RCA COVID -19 Primary and Supplemental Analyses
Parameters Primary Analyses Supplemental Analyses
Vaccine TypesModerna
NovavaxPfizerPfizer & Moderna combinedPfizer with fluPfizer with flu high dose/adjuvant Moderna with fluModerna with flu high dose/adjuvant Pfizer without same day vaccinesModerna without same day vaccines
Risk vs. Comparison Intervals1-21 days vs 43- 63 days
1-42 days vs 43- 84 daysFor myocarditis/pericarditis: 1-21 days vs 22- 42 days
Age Groups0-4 y
5-11 y
12-17 y
18-64 y
≥65 yAllages (≥ 6 months )
18-49 y
50-64 y
60-74 y
≥75 yFor myocarditis/pericarditis:  12-39 y
17
VSD Results
COVID -19 vaccine doses administered in VSD
by manufacturer
19
COVID -19 vaccine doses administered in VSD
by age group
20
COVID -19 vaccine doses administered in VSD
with other vaccines on the same day1
1 Some people received more than two vaccines on the same day. Not all categories are mutually exclusive.
Flu=Influenza vaccine; Tdap=Tetanus, Diphtheria, Pertussis vaccine; RSV=Respiratory syncytial virus vaccine; Zoster=Zoster recom binant vaccine; Pneumo =Pneumococcal vaccine 21
VSD RCA statistical signals
Outcome Moderna Pfizer
Acute disseminated encephalomyelitis (ADEM) No No
Acute myocardial infarction No No
Encephalitis / myelitis / encephalomyelitis
(not ADEM or TM)No No
Guillain -Barré syndrome (GBS) No Yes
Hemorrhagic stroke No No
Ischemic stroke Yes Yes
Immune thrombocytopenia No No
Myocarditis / pericarditis No No
Pulmonary embolism No No
Seizure No No
Transverse myelitis (TM) No No
22
Guillain -Barré syndrome (GBS)
Guillain- Barré syndrome (GBS)
VSD statistical signals
Vaccine Moderna Pfizer
Risk Interval (days) 1 - 21 1 - 42 1 - 21 1 - 42
Age Group (years)
0 –4 No No No No
5 –11 No No No No
12 –17 No No No No
18 –64 No No No No
≥65 No No Yes Yes
24
Characteristics of chart -confirmed GBS cases after
Pfizer COVID -19 vaccine among people aged ≥65 years
CharacteristicRisk Interval cases
Days 1 -42
(n = 7)Comparison Interval cases
Days 43 -84
(n = 3)
Brighton Level1
1 2 0
2 5 3
3 0 0
Age Group (years)
65 – 74 4 1
75 – 84 3 2
≥85 0 0
Same day vaccines
None 5 2
Any 2 1
Influenza 1 1
Influenza + PCV 1 0
1 Sejvar  et al. Guillain -Barré syndrome and Fisher syndrome: case definitions and guidelines for collection, analysis, and presentation of immunization safety data. Vaccine. 2011;29(3):599 -612 25
Chart -confirmed GBS concurrent comparator analysis for
Pfizer COVID -19 vaccine among people aged ≥65 y ears
AnalysisCases in
Risk Interval
(Days 1 -42)Cases in
Comparison Interval
(Days 43 -84)Adjusted Rate
Ratio1
(95% Confidence
Interval)
Pfizer, all doses 7 3 4.45 (1.07–  22.62)
Pfizer without same
day vaccines5 2 4.86 (0.88 – 38.52)
1 Adjusted for outcome calendar date, age group, sex, race/ethnicity, VSD siteEstimated excess GBS cases:  4.1 per million doses
26
•VSD identified a statistical signal for GBS after Pfizer COVID -19 vaccine in adults aged ≥65 years
during the 2023- 2024 season
-The VSD had not identified any signals for GBS with previous mRNA COVID -19 vaccine formulations (i.e.,
original primary series, original booster, or 2022 -2023 bivalent)
-The analysis did not suggest that other vaccines administered on the same day accounted for the
increased rate
•The increased rate ratio observed for Pfizer COVID -19 vaccine during the 2023- 2024 season
may or may not represent a true risk, because a large number of  analyses may find some
associations by chance alone, and surveillance analyses may have residual confounding
•There were insufficient doses of Moderna or Novavax vaccines administered in the VSD to
assess the rate of GBS with those vaccines
-There is not n ecessarily a difference in GBS rate following Pfizer COVID -19 vaccine and the other COVID -
19 vaccinesVSD summary and interpretation for GBS
27
Ischemic stroke
Ischemic stroke
VSD statistical signals
Vaccine Moderna Pfizer
Risk Interval (days) 1 - 21 1 - 42 1 - 21 1 - 42
Age Group (years)
0 –4 No No No No
5 –11 No No No No
12 –17 No No No No
18 –64 No No Yes No
≥65 No Yes No No
29
Ischemic stroke concurrent comparator analysis for
Pfizer  COVID -19 vaccine among people aged 18- 64 years
AnalysisCases in
Risk Interval
(Days 1 -21)Cases in
Comparison Interval
(Days 43 -63)Adjusted Rate
Ratio1
(95% Confidence
Interval)
Ages 18 -49 13 13 1.12 (0.46 – 2.67)
Ages 50 -64 69 57 1.57 (1.06 – 2.31)
1 Adjusted for outcome calendar date, age group, sex, race/ethnicity, VSD site 30
1.57
1.001.98
1.48
1.06
0.181.070.872.314.97
3.70
2.50
0.001.002.003.004.005.006.00
Pfizer   Moderna3
Vaccine without any
same  day vaccinesPfizer     Moderna
Vaccine with or without
same day vaccines Pfizer    Moderna3
Vaccine with same day
influenza  vaccineAdjusted Rate Ratio &
95% Confidence IntervalIschemic stroke supplemental analyses to evaluate statistical signal for
Pfizer  COVID -19 vaccine among people aged  50-64 years
a
Exact Analysis 1 -21 days vs 43- 63 days
Adjusted Rate Ratios and 95% Confidence Intervals1,2
1 Dose totals for age group:  Pfizer = 572,885;  Moderna = 57,012
2 Rate ratios adjusted for outcome calendar date, age group, sex, race/ethnicity, VSD site
3 This analysis not done for Moderna due to small sample size 31
Ischemic stroke concurrent comparator analysis for
Moderna  COVID -19 vaccine among people aged ≥65  years
VaccineCases in
Risk Interval
(Days 1 -42)Cases in
Comparison Interval
(Days 43 -84)Adjusted Rate
Ratio1
(95% Confidence
Interval)
Moderna 53 51 1.53 (0.96 – 2.42)
1 Adjusted for outcome calendar date, age group, sex, race/ethnicity, VSD site 32
Ischemic stroke concurrent comparator analysis for
mRNA  COVID -19 vaccines among people aged ≥65  years
VaccineCases in
Risk Interval
(Days 1 -42)Cases in
Comparison Interval
(Days 43 -84)Adjusted Rate
Ratio1
(95% Confidence
Interval)
Moderna 53 51 1.53 (0.96 – 2.42)
Pfizer 574 714 1.00 (0.88 – 1.14)
1 Adjusted for outcome calendar date, age group, sex, race/ethnicity, VSD site 33
Adjusted Rate Ratio &
95% Confidence Interval
Pfizer      Moderna
Vaccine with or without
same day vaccines Pfizer       Moderna
Vaccine with same day
influenza  vaccinePfizer Moderna
Vaccine without any
same day vaccines1.001.53
1.042.53
0.951.26
0.880.96
0.831.10
0.800.701.142.42
1.295.91
1.132.24
0.001.002.003.004.005.006.007.00Ischemic stroke supplemental analyses to evaluate statistical signal for
Moderna  COVID -19 vaccine among people aged ≥65  years
a
Exact Analysis 1 -42 days vs 43- 84 days
Adjusted Rate Ratios and 95% Confidence Intervals1,2
1 Dose totals for age group:  Pfizer = 953,559;  Moderna = 81,553
2 Rate ratios adjusted for outcome calendar date, age group, sex, race/ethnicity, VSD site 34
•VSD detected statistical signals for ischemic stroke for Pfizer and Moderna COVID -19 vaccines
during the 2023- 2024 season
-There was a lack of consistent findings across age groups or risk interv als
-There was not a significantly different risk associated with receipt of simultaneous influenza vaccine
•The VSD previously identified a statistical signal for ischemic stroke for the 2022 -2023 bivalent
formulation of Pfizer vaccine in the ≥65 years age group using the 1-21 day  risk interval
•This season’s findings are consistent with CDC Immunization Safety Office’s prior
interpretation based on data review in October 2023 that stated: “Available data do not provide clear and consistent evidence of a safety problem for ischemic stroke with
bivalent mRNA COVID -19 vaccines when given alone or given simultaneously with influenza
vaccines”
1
•The statistical signals during the 2022 -20232 and the 2023- 2024 seasons require further
evaluation
-The VSD has a follow -up retrospective study in progress to further assess the risk of ischemic strokeVSD summary and interpretation for ischemic stroke
1 Shimabukuro TS, presentation to ACIP, October 25, 2023. Available at: https://www.cdc.gov/vaccines/acip/meetings/downloads/sl ides-2023 -10-25-26/01 -VaxSafety -Shimabukuro -508.pdf
2 Klein NK, presentation to ACIP, September 12, 2023. Available at: https://www.cdc.gov/vaccines/acip/meetings/downloads/slides -2023 -09-12/07 -COVID -Klein -508.pdf 35
Conclusions
•Rates of local and/or systemic reactions reported by V -safe participants
during the first week after receiving a dose of the 2023- 2024 COVID- 19
vaccine were similar to  last season
•VSD identified statistical signals for GBS and ischemic stroke
•No other new or unexpected safety concerns were identified for the 2023-
2024 COVID- 19 vaccines by VAERS, V- safe, or VSDConclusions
37
•The increased rate ratio of GBS following Pfizer COVID- 19 vaccine among people aged ≥65 years
observed during the 2023 -2024 season may or may not represent a true risk
-If there is a true risk, then t he estimated excess GBS cases of 4.1 per million doses is similar to
previous estimates for other vaccines for adults
•Influenza:  1 - 2 cases per million doses1
•Recombinant Zoster Vaccine:  3 - 6 cases per million doses2
•The VSD statistical signals for ischemic stroke after mRNA COVID- 19 vaccines during the 2023 -2024
season do not provide sufficient evidence to conclude that there is a safety concern. A follow -up VSD
study is in progress to further examine the risk of ischemic stroke after mRNA COVID- 19 vaccines
•FDA’s 2023- 2024 COVID -19 vaccine safety surveillance using commercial health plans and Medicare
claims databases results are expected later this year, which will provide additional information about
GBS, stroke, and other outcomesConclusions
381 Perez -Vilar S, et al. Guillain -Barré Syndrome After High -Dose Influenza Vaccine Administration in the United States, 2018 -2019 Season . J Infect Dis. 2021 Feb 13;223(3):416 -425.
2 Janusz CB, et al. Projected risks and health benefits of vaccination against herpes zoster and related complications in US adults . Human Vaccines & Immunotherapeutics , 18(5), 2022.
•Any real or theoretical risks of vaccine adverse events need to be placed in
the context of the benefits of COVID -19 vaccines in preventing COVID- 19
and its potentially serious complications
•CDC and FDA will continue to monitor the safety of COVID- 19 vaccinesConclusions
39
Acknowledgments
•CDC Immunization Safety Office:
-Karen Broder, Hannah Brown, Carol Ennulat , Anne Hause,
Tat’Yana Kenigsberg, Paige Marquez, Mike McNeil, Pedro
Moro, Tanya Myers, Brittney Romanson, David Shay, John Su, Lily Wang, Kimp Walton, Eric Weintraub, Bicheng (Tony)
Zhang
•Kaiser Permanente Northern California:
-Ned Lewis, Nicky Klein, Joan Bartlett, Kristin Goddard, Bruce
Fireman, Ousseny Zerbo
•Marshfield Clinic Research Institute:
-Jim Donahue, Kayla Hanson, Ed Belongia, Burney Kieke, Dave McClure, Erica Scotty•VSD Sites
• Denver Health, Denver, Colorado
• HealthPartners Institute, Minneapolis, Minnesota
• Kaiser Permanente Colorado, Denver, Colorado
• Kaiser Permanente Mid Atlantic, Rockville Maryland
• Kaiser Permanente Northern California, Oakland, California
• Kaiser Permanente Northwest, Portland, Oregon
• Kaiser Permanente Southern California, Los Angeles, California
• Kaiser Permanente Washington, Seattle, Washington
• Marshfield Clinic Research Institute, Marshfield, Wisconsin
•FDA Center for Biologics Evaluation and Research,
Office of Biostatistics and Pharmacovigilance
40
For more information, contact CDC
1-800- CDC- INFO (232 -4636)
TTY:  1 -888- 232- 6348    www.cdc.gov
The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Summary: COVID -19 vaccine safety surveillance  for the 2023 -2024 season Jonathan Duffy, MD, MPH Immunization Safety Office June 27, 2024National Center for Emerging and Zoonotic Infectious Diseases  •Vaccine Adverse Event Reporting System (VAERS) •V-s afe •Vaccine Safety Datalink (VSD)CDC surveillance systems monitoring COVID -19  vaccine safety  2 •The Vaccine Safety Datalink (VSD) identified two statistical signals for mRNA COVID- 1 9 vaccines  during the 2023 -2024 season -Guillain -B arré…