Document text
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