1

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.

Updates to COVID-19 vaccine effectiveness (VE) in 

the U.S

September 12, 2023

Ruth Link-Gelles, PhD, MPH

CDR, US Public Health Service

COVID-19 Vaccine Effectiveness Program Lead

Centers for Disease Control and Prevention
2

▪ Included today:

– VE against emergency department/urgent care encounters in young children

– VE against emergency department/urgent care encounters in older children, adolescents, and adults

– VE against hospitalization and critical illness in adults

▪ Note: updates in this presentation are meant to complement results of the GRADE 

presentation

Organization of presentation
3

▪ High rates of infection-induced immunity 

by July–August 2022.*

▪ VE findings should be interpreted as the 

incremental benefit provided by COVID-19 

vaccination in a population with a high 

prevalence of infection-induced immunity.

Context for interpreting VE across age groups

* https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2023-06-21-23/03-COVID-Jones-508.pdf; data on children aged 6 months – 17 years is from cross-sectional blood specimens collected by 

commercial laboratories. Data on persons aged ≥16 years is from a longitudinal, national cohort of >70,000 blood donors.

Age group

% with infection-induced 

immunity

6-11 month 66%

12-23 months 74%

2-4 years 83%

5-11 years 88%

12-17 years 86%

16-29 years 83%

30-49 years 78%

50-64 years 68%

≥65 years 48%
4

Vaccine effectiveness in young children

VISION Network (emergency department/urgent care encounters)

Updates based on analyses in recent MMWR:

• Link-Gelles R, Ciesla AA, Rowley EA, et al. Effectiveness of Monovalent and Bivalent mRNA Vaccines in Preventing 

COVID-19–Associated Emergency Department and Urgent Care Encounters Among Children Aged 6 Months–5 

Years —VISION Network, United States, July 2022–June 2023. MMWR Morb Mortal Wkly Rep 2023;72:886–892. 

DOI: http://dx.doi.org/10.15585/mmwr.mm7233a2
5

VISION Multi-Site Network of Electronic Health Records

▪ Design: Test-negative case-control

▪ Population: Immunocompetent children 

aged 6 months – 4 or 5 years visiting a 

participating emergency department or 

urgent care (ED/UC) with COVID-19-like 

illness (CLI) with a SARS-CoV-2 NAAT test 

result within 14 days before or 72 hours 

after encounter

− Cases: CLI with positive NAAT for SARS-CoV-2

− Controls: CLI with negative NAAT for SARS-CoV-2

▪ Vaccination data: Documented by electronic health records and state 

and city registries

▪ Dates of analysis: July 2022 –August 2023
6

VISION: Estimates of VE for original monovalent Moderna primary series vaccine 

(children aged 6 months–5 years) against ED/UC encounters, July 4, 2022 – August 9, 

2023*

Vaccination status (months since last dose) Total tests SARS-CoV-2

positive, N (%)

Median interval since 

last dose, days (IQR)

Adjusted

VE (95% CI)

Moderna, 1 dose (partial series; ages 6mo–5 years)

July 4, 2022–June 17, 2023

Unvaccinated 90,737 4,966 (5.5) NA Ref

1 (original) monovalent dose (≥14 days) 1,053 47 (4.5) 66 (30–127) 23 (−3 to 43)

Moderna, 2 doses (complete series; ages 6mo–5 years)

August 1, 2022–June 17, 2023

Unvaccinated 85,746 4,061 (4.7) NA Ref

2 (original) monovalent doses (≥14 days) 3,736 98 (2.6) 105 (64–169) 31 (15 to 44)

2 (original) monovalent doses (14-59 days) 811 23 (2.8) 38 (26–49) 46 (17 to 64)

2 (original) monovalent doses (≥60 days) 2,925 75 (2.6) 124 (91–193) 24 (4 to 40)

-40 -20 0 20 40 60 80 100

Vaccine Effectiveness (%)

* Different analysis periods were used for each product and dose number because vaccinated children became eligible to be included 14 days after the dose at different times: 1 

dose of Moderna and Pfizer-BioNTech on July 4, 2022; 2 doses of Pfizer-BioNTech on July 25, 2022; 2 doses of Moderna on August 1, 2022; 3 doses of Pfizer-BioNTech on 

September 19, 2022; bivalent doses on December 24, 2022.
7

VISION: Estimates of VE for original monovalent Pfizer-BioNTech primary series vaccine (children 

aged 6 months–4 years) against ED/UC encounters, July 4, 2022 – June 17, 2023

Vaccination status (months since last dose) Total tests SARS-CoV-2

positive, N (%)

Median interval since 

last dose, days (IQR)

Adjusted

VE (95% CI)

Pfizer, 1 dose (partial series; ages 6mo–4 years)

July 4, 2022–June 17, 2023

Unvaccinated 79,480 4,632 (5.8) NA Ref

1 (original) monovalent dose (≥14 days) 1,640 78 (4.8) 60 (29–112) 8 (−16 to 27)

Pfizer, 2 doses (partial series; ages 6mo–4 years)

July 25, 2022–June 17, 2023

Unvaccinated 75,965 3,990 (5.2) NA Ref

2 (original) monovalent doses (≥14 days) 2,682 78 (2.9) 70 (41–121) 34 (16 to 47)

2 (original) monovalent doses (14-59 days) 1,138 34 (3.0) 37 (25–47) 44 (21 to 61)

2 (original) monovalent doses (≥60 days) 1,544 44 (2.9) 111 (82–164) 23 (−5 to 43)

Pfizer, 3 doses (complete series; ages 6mo–4 years)

September 19, 2022–June 17, 2023

Unvaccinated 66,847 2,992 (4.5) NA Ref

3 (original) monovalent doses (≥14 days) 1,542 33 (2.1) 82 (43–153) 38 (12 to 56)

3 (original) monovalent doses (14-59 days) 573 6 (1.1) 35 (26–46) 71 (36 to 87)**

3 (original) monovalent doses (≥60 days) 969 27 (2.8) 132 (89–187) 16 (−24 to 43)**

-40 -20 0 20 40 60 80 100

Vaccine Effectiveness (%) * Different analysis periods were used for each product and dose number because vaccinated children became eligible to be included 14 days after the dose at different times: 1 dose of Moderna and 

Pfizer-BioNTech on July 4, 2022; 2 doses of Pfizer-BioNTech on July 25, 2022; 2 doses of Moderna on August 1, 2022; 3 doses of Pfizer-BioNTech on September 19, 2022; bivalent doses on December 24, 

2022.

** This estimate is imprecise, which might be due to there being 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 increase precision and allow more precise interpretation.
8

VISION: Estimates of VE for ≥1 bivalent vaccine (children aged 6 months–4 or 5 years) against ED/UC 

encounters, December 24, 2022 – June 17, 2023

Vaccination status (months since last dose) Total tests SARS-CoV-2

positive, N (%)

Median interval since 

last dose, days (IQR)

Adjusted

VE (95% CI)

Regardless of manufacturer, ≥1 bivalent dose (ages 6mo–5 years)

Unvaccinated 34,582 1,505 (4.3) NA Ref

≥1 bivalent dose (≥14 days) 458 8 (1.8) 66 (39–103) 61 (22 to 83)**

-60 -40 -20 0 20 40 60 80 100

Vaccine Effectiveness (%)

*This estimate was calculated using unadjusted exact methods due to the small number of vaccinated case-patients. Five vaccinated case-patients received bivalent Pfizer-BioNTech doses and three received Moderna 

doses; vaccinated control-patients included those who received both bivalent Moderna (126) and Pfizer-BioNTech (324) doses.

This estimate is imprecise, which might be due to there being 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 increase precision and allow more precise interpretation.

Children included in the bivalent analysis were either unvaccinated (received 0 COVID-19 vaccine doses) or had received ≥1 bivalent vaccine dose from either manufacturer. Among those who received a bivalent 

vaccine dose, any combination of original monovalent and bivalent doses was included, but at minimum children had to have received 2 Moderna doses or 3 Pfizer-BioNTech doses (i.e., a complete primary series). 
9

▪ 1 dose of original monovalent Moderna or Pfizer-BioNTech vaccines did not provide 

significant protection

▪ 2 doses of either product (and 3 doses of Pfizer-BioNTech) provided protection against 

ED/UC and hospitalization, though waning was evident (similar to older children and 

adults)

▪ A bivalent dose provided protection, though sample size was limited.

▪ Median interval since receipt of the most recent dose among children who had not 

completed their primary series was longer than expected based on the recommended 

dosing intervals → some children not completing primary series

Conclusions: Vaccine effectiveness in young children
10

Updates to bivalent vaccine effectiveness

VISION Network

Updates based on analyses in recent MMWRs:

Link-Gelles, et al. Estimates of Bivalent mRNA Vaccine Durability in Preventing COVID-19–Associated Hospitalization 

and Critical Illness Among Adults with and Without Immunocompromising Conditions —VISION Network, September 

2022–April 2023. https://www.cdc.gov/mmwr/volumes/72/wr/mm7221a3.htm

IVY Network

Updates based on analyses in recent MMWR:

• DeCuir, Surie, et al. MMWR. Effectiveness of Monovalent mRNA COVID-19 Vaccination in Preventing COVID-19–

Associated Invasive Mechanical Ventilation and Death Among Immunocompetent Adults During the Omicron 

Variant Period — IVY Network, 19 U.S. States, February 1, 2022–January 31, 2023. 

https://www.cdc.gov/mmwr/volumes/72/wr/mm7217a3.htm
11

VISION Multi-State Network of Electronic Health Records

▪ Design: Test-negative case-control

▪ Population: Persons admitted to a 

participating emergency department, 

urgent care, or hospital with COVID-19-like 

illness (CLI) with a SARS-CoV-2 NAAT test 

result within 14 days before or 72 hours 

after encounter or admission

− Cases: CLI with positive NAAT for SARS-CoV-2

− Controls: CLI with negative NAAT for SARS-CoV-2

▪ Vaccination data: Documented by electronic health records and state 

and city registries

▪ Dates of analysis: September 2022 –August 2023
12

VISION: AbsoluteVE of original monovalent and bivalent booster doses 

against ED/UC encounters among immunocompetent persons, by age 

group – September 2022 –August 2023

VE estimates adjusted for age, sex, race and ethnicity, geographic region, and calendar time. CDC unpublished data

mRNA Dosage Pattern Total

tests

SARS-CoV-2-

test-positive,

N (%)

Median interval

since last dose,

days (IQR)

Adjusted VE (95% CI)

Unvaccinated

5-17 years 41,910 1,446 (4) -- Ref

18-64 years 90,349 8,201 (9) -- Ref

≥65 years 17,108 2,453 (14) -- Ref

Original monovalent doses only

5-17 years 28,369 1,092 (4) 334 (253-439) 7 (-1 to 15)

18-64 years 14,9267 14,270 (10) 441 (334-564) 2 (-1 to 5)

≥65 years 69,989 8,538 (12) 383 (266-531) 17 (12 to 21)

Bivalent booster, 7-59 days earlier

5-17 years 1,858 30 (2) 30 (18-44) 63 (46 to 74)

18-64 years 9,763 549 (6) 33 (21-46) 56 (52 to 60)

≥65 years 1,1826 970 (8) 35 (21-48) 59 (55 to 62)

Bivalent booster, 60-119 days earlier

5-17 years 1,268 37 (3) 89 (74-105) 36 (10 to 54)

18-64 years 9,558 682 (7) 86 (72-102) 39 (34 to 44)

≥65 years 12,753 1,255 (9) 87 (73-102) 47(42 to 51)

-20 0 20 40 60 80 100

Vaccine Effectiveness (%)
13

VISION: AbsoluteVE of original monovalent and bivalent booster doses 

against hospitalization among immunocompetent adults, by age group –

September 2022 –August 2023

VE estimates adjusted for age, sex, race and ethnicity, geographic region, and calendar time. Updated from: Link-Gelles et al., MMWR, https://www.cdc.gov/mmwr/volumes/72/wr/mm7221a3.htm

* These estimates are imprecise, which might be due to there being 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 increase precision and allow more precise 

interpretation.

mRNA Dosage Pattern Total

tests

SARS-CoV-2-

test-positive,

N (%)

Median interval

since last dose,

days (IQR)

Adjusted VE

(95% CI)

18-64 years

Unvaccinated (ref) 13,089 803 (6) -- Ref

Original monovalent doses only 19,799 1,129 (6) 455 (333-575) 15 (6 to 23)

Bivalent booster, 7-59 days earlier 1,208 45 (4) 33 (21-45) 61 (46 to 71)

Bivalent booster, 60-119 days earlier 1,248 87 (7) 87 (73-102) 15 (-8 to 33)

Bivalent booster, 120-179 days earlier 1,075 59 (6) 147 (134-163) -1 (-35 to 24)*

≥65 years

Unvaccinated (ref) 12,015 1,688 (14) -- Ref

Original monovalent doses only 37,001 4,216 (11) 402 (288-555) 25 (20-30)

Bivalent booster, 7-59 days earlier 4,607 328 (7) 35 (21-48) 67 (62-71)

Bivalent booster, 60-119 days earlier 5,252 490 (9) 88 (73-104) 53 (48-58)

Bivalent booster, 120-179 days earlier 4,482 415 (9) 149 (134-164) 28 (18-36)

-40 -20 0 20 40 60 80 100

Vaccine Effectiveness (%)
14

VISION: AbsoluteVE of original monovalent and bivalent booster doses 

against hospitalization and critical illness among immunocompetent

adults aged ≥18 years – September 2022 – August 2023

Critical illness defined as admission to intensive care unit or death; case-patients were persons admitted to ICU or who experienced death associated with COVID-19, and 

control patients were persons hospitalized without COVID-19. VE estimates adjusted for age, sex, race and ethnicity, geographic region, and calendar time. Updated from: LinkGelles et al., MMWR, https://www.cdc.gov/mmwr/volumes/72/wr/mm7221a3.htm

mRNA Dosage Pattern Total

tests

SARS-CoV-2-

test-positive,

N (%)

Median interval

since last dose,

days (IQR)

Adjusted VE

(95% CI)

Hospitalization

Unvaccinated (ref) 25,104 2,491 (10) -- Ref

Original monovalent doses only 56,800 5,345 (9) 420 (306-563) 22 (17-26)

Bivalent booster, 7-59 days earlier 5,815 373 (6) 34 (21-47) 65 (61-69)

Bivalent booster, 60-119 days earlier 6,500 577 (9) 87 (73-103) 48 (42-53)

Bivalent booster, 120-179 days earlier 5,557 474 (9) 149 (134-164) 22 (13-30)

Critical illness

Unvaccinated (ref) 23,140 527 (2) -- Ref

Original monovalent doses only 52,352 897 (2) 422 (306-564) 32 (23-40)

Bivalent booster, 7-59 days earlier 5,504 62 (1) 34 (21-47) 69 (59-77)

Bivalent booster, 60-119 days earlier 6,023 100 (2) 87 (73-103) 50 (36-60)

Bivalent booster, 120-179 days earlier 5,144 61 (1) 149 (134-164) 46 (28-60)

-20 0 20 40 60 80 100

Vaccine Effectiveness (%)
15

VISION: AbsoluteVE of original monovalent and bivalent booster doses 

against hospitalization among adults ≥18 years, by immunocompromise 

status – September 2022 – August 2023

VE estimates adjusted for age, sex, race and ethnicity, geographic region, and calendar time. Updated from: Link-Gelles et al., MMWR, 

https://www.cdc.gov/mmwr/volumes/72/wr/mm7221a3.htm

mRNA Dosage Pattern Total

tests

SARS-CoV-2-

test-positive,

N (%)

Median interval

since last dose,

days (IQR)

Adjusted VE

(95% CI)

Without immunocompromising conditions

Unvaccinated (ref) 25,104 2,491 (10) -- Ref

Original monovalent doses only 56,800 5,345 (9) 420 (306-563) 22 (17-26)

Bivalent booster, 7-59 days earlier 5,815 373 (6) 34 (21-47) 65 (61-69)

Bivalent booster, 60-119 days earlier 6,500 577 (9) 87 (73-103) 48 (42-53)

Bivalent booster, 120-179 days earlier 5,557 474 (9) 149 (134-164) 22 (13-30)

With immunocompromising conditions

Unvaccinated (ref) 5,044 440 (9) -- Ref

Original monovalent doses only 16,937 1,575 (9) 397 (276-539) 1 (-11-12)

Bivalent booster, 7-59 days earlier 1,970 168 (9) 34 (20-47) 31 (16-43)

Bivalent booster, 60-119 days earlier 2,336 172 (7) 88 (74-104) 40 (27-50)

Bivalent booster, 120-179 days earlier 2,188 166 (8) 149 (134-164) 12 (-7-28)

-20 0 20 40 60 80 100

Vaccine Effectiveness (%)
16

IVY Network — 25 hospitals, 20 U.S. States

▪ Design: Prospective, case-control

▪ Population: Adults aged ≥18 years hospitalized with 

Acute respiratory illness (ARI)*

– Cases: ARI and test positive for SARS-CoV-2 by NAAT or 

antigen test within 10 days of illness

– Controls: ARI and test negative for SARS-CoV-2 and influenza 

by NAAT within 10 days of illness

▪ Vaccination data: Electronic medical records (EMR), 

state and city registries, and self-report

▪ Specimens: Upper respiratory specimens obtained 

for central RT-qPCR testing and sequencing

▪ Dates of analysis: September 2022 – May 2023

*ARI is defined as presence of any one of the following: fever, cough, shortness of breath, chest imaging consistent with pneumonia, hypoxemia
17

IVY: AbsoluteVE against COVID-19 hospitalization among 

immunocompetent adults aged ≥18 years — September 8, 2022 – May 

31, 2023

Case vaccination 

status, no. (%)

Control 

vaccination 

status, no. (%)

Median time

since last dose,

days (IQR)

Adjusted VE*,

% (95% CI)

18–64 years N=927 N=1,680

Unvaccinated 307 (33) 483 (29) -- Ref

Original monovalent doses only 514 (55) 979 (58) 412 (297–533) 20 (4–34)

Bivalent booster dose, 7–89 days earlier 48 (5) 123 (7) 54 (33–71) 43 (16–62) 

Bivalent booster dose, 90–179 days earlier 58 (6) 95 (6) 130 (110–151) 17 (-28 to 46)** 

≥65 years N=1,556 N=1,971

Unvaccinated 238 (15) 274 (14) -- Ref

Original monovalent doses only 992 (64) 1108 (56) 385 (278–510) 1 (-20 to 19)

Bivalent booster dose, 7–89 days earlier 131 (8) 329 (17) 52 (29–68) 53 (37–66) 

Bivalent booster dose, 90–179 days earlier 195 (13) 260 (13) 130 (109–151) 10 (-24 to 35)** 

*VE adjustments: Age, sex, race/ethnicity, admission date (biweekly), and HHS region

** These estimates are imprecise, which might be due to there being 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 increase precision and 

allow more precise interpretation.

-40 -20 0 20 40 60 80 100

Vaccine Effectiveness (%)
18

IVY: AbsoluteVE against COVID-19 hospitalization among adults 

aged ≥18 years, by immunocompromise status — September 8, 2022 

– May 31, 2023

Case vaccination 

status, no. (%)

Control 

vaccination 

status, no. (%)

Median time

since last dose,

days (IQR)

Adjusted VE*,

% (95% CI)

Immunocompetent n=2,483 n=3,651

Unvaccinated 545 (22) 757 (21) -- Ref

Original monovalent doses only 1506 (61) 2087 (57) 395 (286–521) 10 (-4 to 21)

Bivalent booster dose, 7–89 days earlier 179 (7) 452 (12) 53 (30–69) 51 (37–61)

Bivalent booster dose, 90–179 days earlier 253 (10) 355 (10) 130 (109–151) 12 (-12 to 31) 

Immunocompromised n=809 n=1,257

Unvaccinated 132 (16) 182 (14) -- Ref

Original monovalent doses only 543 (67) 767 (61) 374 (256–504) 13 (-14 to 33)

Bivalent booster dose, 7–89 days earlier 59 (7) 160 (13) 46 (26–72) 55 (29–71) 

Bivalent booster dose, 90–179 days earlier 75 (9) 148 (12) 126 (107–152) 43 (7–65)**

-20 0 20 40 60 80 100

* VE adjustments: Age, sex, race/ethnicity, admission date (biweekly), and HHS region Vaccine Effectiveness (%)

** These estimates are imprecise, which might be due to there being 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 increase precision and allow more precise interpretation.
19

▪ VE waning against hospitalization and ED/UC; more sustained protection against critical 

illness

– Difficult to separate impact of time since vaccination from emergence of new variants

▪ Patterns are similar across age groups, though low uptake of bivalent doses in younger age 

groups prevented assessment of waning beyond 4 months from the bivalent dose.

▪ Persons with immunocompromise may have reduced protection after COVID-19 vaccination, 

compared with persons without immunocompromise. Historically, COVID-19 VE has been 

lower and waned more quickly for adults with immunocompromise compared to adults 

without immunocompromise. Trends in bivalent VE are less clear and additional data are 

needed.

▪ VE findings should be interpreted as the incremental benefit provided by COVID-19 

vaccination in a population with a high prevalence of infection-induced immunity.

Conclusions: Updates to waning of bivalent vaccine 

effectiveness
20

CDC COVID-19 Vaccine Effectiveness 

and Policy Team

▪ Amadea Britton

▪ Allison Ciesla

▪ Monica Godfrey

▪ Eric Griggs

▪ Katherine Fleming-Dutra

▪ Dani Moulia

▪ Morgan Najdowski

▪ Erica Okwuazi

VE platforms teams, including:

▪ Sarah Ball

▪ Angela Campbell

▪ Jennifer DeCuir

▪ Monica Dickerson

▪ Margaret Dunne

▪ Kiara Everett

▪ Shikha Garg

▪ Victoria Lazariu

▪ Patrick Mitchell

▪ Palak Patel

And many more!!!

Acknowledgements

▪ Heidi Moline

▪ Caitlin Ray

▪ Sarah Reese

▪ Elizabeth Rowley

▪ Regina Simeone

▪ Zach Smith

▪ Diya Surie

▪ Mark Tenforde

▪ Zack Weber

▪ Laura Zambrano

▪ Josephine Mak

▪ Amanda Payne

▪ Lauren Roper

▪ Laura Steinhardt

▪ Megan Wallace

▪ Ryan Wiegand
21

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.

Questions?
22

Back-up
23

New Vaccine Surveillance Network (NVSN)

Design: active, prospective, population-based ARI surveillance network for pediatric viral 

infections at 7 medical centers.

Study population: Children <18 years with ARI are enrolled year-round in the outpatient,

ED, and hospital settings. Healthy controls are enrolled in the outpatient setting (well

child visits).

▪ 5794 children 6mos-4yrs with acute respiratory illness during July 1, 2022 —June 30, 2023

Data collection: Demographic and clinical data are collected through parent/guardian 

interviews and medical chart reviews, and laboratory testing. Vaccine status verified through 

state immunization registries and primary care record review.

NVSN COVID-19 Vaccine Effectiveness Methodology

– Test-negative design. All enrolled children are tested for 8 respiratory viruses.

– Cases = SARS-CoV-2 positive, controls = SARS-CoV-2 negative.

– Regression models adjusted for study site, sex, race, and calendar time (week of enrollment). 

– Vaccine status was defined as 1) unvaccinated = received zero COVID-19 vaccine doses of any product, 2) one dose only = received 

one COVID-19 vaccine dose of any product, or 3) two or more doses = received two or more COVID-19 vaccine doses of any 

product. Children within two weeks of vaccine receipt were excluded. 
24

New Vaccine Surveillance Network (NVSN): VE of any product 

against emergency department visits and hospitalization, 

children 6 months – 4 years, July 2022-June, 2023

Case vaccination 

status (n=291)

Control vaccination 

status (n=5,503)

Median time

since last dose,

days (IQR)

Adjusted VE*,

% (95% CI)

Unvaccinated 260 (89) 4,691 (85) NA

Vaccinated with ≥1 dose* 31 (11) 812 (15) Not calculated Not calculated

One dose 10 (3) 228 (4) 61 (31-105) 30 (-36-64)**

Two doses 21 (7) 584 (11) 74 (42-131) 40 (3-63)**

-40 -20 0 20 40 60 80 100

Vaccine Effectiveness (%)

* Vaccine status was defined as 1) unvaccinated = received zero COVID-19 vaccine doses of any product, 2) one dose only = received one COVID-19 vaccine dose of any product, or 3) two 

or more doses = received two or more COVID-19 vaccine doses of any product. Children within two weeks of vaccine receipt were excluded. 

** These estimates are imprecise, which might be due to there being 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 increase precision and allow 

more precise interpretation.
25

IVY: AbsoluteVE against COVID-19 hospitalization among 

immunocompetent adults aged ≥18 years by SARS-CoV-2 

subvariant predominance— September 8, 2022 – May 31, 2023

Case vaccination 

status, no. (%)

Control 

vaccination status, 

no. (%)

Median time

since last dose,

days (IQR)

Adjusted VE*,

% (95% CI)

BA.4/5 (September 8 – November 26, 2022) n=688 n=989

Unvaccinated 169 (25) 199 (20)

Original monovalent doses only 479 (70) 692 (70) 311 (195–403) 32 (12–47)

Bivalent booster dose, 7–89 days earlier 40 (6) 98 (10) 29 (16-45) 68 (46–81)

BQ.1 (November 27, 2022 – January 17, 2023) n=622 n=1,080

Unvaccinated 145 (23) 223 (21)

Original monovalent doses only 399 (64) 617 (57) 388 (306–517) 12 (-14 to 32)

Bivalent booster dose, 7–89 days earlier 78 (13) 240 (22) 55 (37-69) 54 (33–68)

XBB.1.5 (January 18 – May 31, 2023) n=1,148 n=1,529

Unvaccinated 231 (20) 335 (22)

Original monovalent doses only 628 (55) 778 (51) 464 (374–593) -10 (-35 to 10)

Bivalent booster dose, 7–89 days earlier 61 (5) 114 (7) 65 (46–80) 33 (0–54)**

Bivalent booster dose, 90–179 days earlier 228 (20) 302 (20) 136 (116–154) -7 (-41 to 19)**

*VE adjustments: Age, sex, race/ethnicity, admission date (biweekly), and HHS region

** These estimates are imprecise, which might be due to there being 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 increase precision and allow more precise interpretation.

-60 -40 -20 0 20 40 60 80 100

Vaccine Effectiveness (%)
26

VISION: AbsoluteVE of original monovalent and bivalent booster doses 

against hospitalization and critical illness among immunocompetent

adults aged ≥18 years, during XBB predominance – January – July 2023

CDC unpublished data. VE estimates adjusted for age, sex, race and ethnicity, geographic region, and calendar time.

Variant predominance based on regional circulation: https://covid.cdc.gov/covid-data-tracker/#variant-proportions

* These estimates are imprecise, which might be due to there being 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 increase precision and allow more precise interpretation.

mRNA Dosage Pattern Total

tests

SARS-CoV-2-

test-positive,

N (%)

Median interval

since last dose,

days (IQR)

Adjusted VE

(95% CI)

Hospitalization

Unvaccinated (ref) 10,443 700 (7) -- Ref

Original monovalent doses only 23,140 1,662 (7) 511 (411-639) 13 (5-22)

Bivalent booster, 7-59 days earlier 701 33 (5) 38 (23-49) 57 (38-70)

Bivalent booster, 60-119 days earlier 2,350 165 (7) 98 (83-110) 42 (31-52)

Bivalent booster, 120-179 days earlier 5,067 434 (9) 150 (136-165) 21 (9-31)

Critical illness

Unvaccinated (ref) 9,890 147 (2) -- Ref

Original monovalent doses only 21,751 273 (1) 512 (412-640) 25 (7-40)

Bivalent booster, 7-59 days earlier 674 6 (1) 38 (23-49) 58 (4-82)*

Bivalent booster, 60-119 days earlier 2,211 26 (1) 98 (83-110) 49 (20-67)

Bivalent booster, 120-179 days earlier 4,690 57 (1) 150 (136-165) 44 (22-60)

-20 0 20 40 60 80 100

Vaccine Effectiveness (%)
27

VISION: AbsoluteVE of original monovalent and bivalent booster doses against 

hospitalization among immunocompetent adults aged ≥18 years, by SARS-CoV-2 

subvariant predominance – September 2022 –August 2023

CDC unpublished data. VE estimates adjusted for age, sex, race and ethnicity, geographic region, and calendar time.

Variant predominance based on regional circulation: https://covid.cdc.gov/covid-data-tracker/#variant-proportions

mRNA Dosage Pattern Total

tests

SARS-CoV-2-

test-positive,

N (%)

Median interval

since last dose,

days (IQR)

Adjusted VE

(95% CI)

BA.4/BA.5 predominance (September 2022 – November 2022)

Unvaccinated (ref) 5427 606 (11) -- Ref

Original monovalent doses only 14521 1377 (10) 312 (183-397) 28 (19-35)

Bivalent booster, 7-59 days earlier 1856 129 (7) 25 (15-37) 58 (49-66)

BQ.1 predominance (December 2022 – January 2023)

Unvaccinated (ref) 4,193 619 (15) -- Ref

Original monovalent doses only 9,787 1,300 (13) 390 (296-495) 28 (19-35)

Bivalent booster, 7-59 days earlier 1,870 133 (7) 41 (28-51) 69 (62-75)

Bivalent booster, 60-119 days earlier 2,780 288 (10) 82 (71-94) 52 (44-59)

XBB predominance (February 2023 – August 2023)

Unvaccinated (ref) 10,443 700 (7) -- Ref

Original monovalent doses only 23,140 1,662 (7) 511 (411-639) 13 (5-22)

Bivalent booster, 7-59 days earlier 701 33 (5) 38 (23-49) 57 (38-70)

Bivalent booster, 60-119 days earlier 2,350 165 (7) 98 (83-110) 42 (31-52)

Bivalent booster, 120-179 days earlier 5,067 434 (9) 150 (136-165) 21 (9-31)

-20 0 20 40 60 80 100

Vaccine Effectiveness (%)
28

VISION: AbsoluteVE of original monovalent and bivalent booster doses 

against ED/UC encounters among immunocompetent children and 

adolescents, by age group – September 2022 –August 2023

VE estimates adjusted for age, sex, race and ethnicity, geographic region, and calendar time. Updated from: Link-Gelles et al., MMWR, https://www.cdc.gov/mmwr/volumes/72/wr/mm7221a3.htm

* These estimates are imprecise, which might be due to there being 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 increase precision and allow more precise 

interpretation.

mRNA Dosage Pattern Total

tests

SARS-CoV-2-

test-positive,

N (%)

Median interval

since last dose,

days (IQR)

Adjusted VE

(95% CI)

5-17 years

Unvaccinated (ref) 41,910 1,446 (4) -- Ref

Original monovalent doses only 28,369 1,092 (4) 334 (253-439) 7 (-1 to 15)

Bivalent booster, 7-59 days earlier 1,858 30 (2) 30 (18-44) 63 (46 to 74)

Bivalent booster, 60-119 days earlier 1,268 37 (3) 89 (74-105) 36 (10 to 54)

5-11 years

Unvaccinated (ref) 31,608 905 (3) -- Ref

Original monovalent doses only 14,956 396 (3) 309 (193-368) 13 (2 to 24)

Bivalent booster, 7-59 days earlier 1,004 13 (1) 29 (17-42) 62 (34 to 78)

12-17 years

Unvaccinated (ref) 10302 541 (5) -- Ref

Original monovalent doses only 13413 696 (5) 394 (291-496) 2 (-11 to 13)

Bivalent booster, 7-59 days earlier 854 17 (2) 32 (19-47) 64 (40 to 78)

-40 -20 0 20 40 60 80 100

Vaccine Effectiveness (%)
29

Updated estimates of VE against 

symptomatic infection among children and 

adolescents aged 5–17 and adults aged ≥18 

years

29
30

▪ Absolute VE: comparing the frequency of health outcomes in vaccinated and 

unvaccinated people 

– E.g., comparing outcomes in people vaccinated with an updated bivalent booster versus no 

vaccine at all

▪ Relative VE: comparing the frequency of health outcomes in people who received 

one type of vaccine to people who received a different vaccine or by comparing 

people who received more vaccine doses to those who received fewer doses 

– E.g., comparing outcomes in people vaccinated with an updated bivalent booster versus 

monovalent vaccine only

▪ In the analyses presented today, relative vaccine effectiveness can be interpreted as 

the additional protection provided by an updated bivalent booster among people 

who already received monovalent COVID-19 vaccines

Interpreting absolute and relative vaccine effectiveness 
31

▪ Nationwide community-based drive-through SARS-CoV-2 testing via pharmacies

▪ Self-reported vaccine history at time of registration for COVID-19 testing

▪ Design: Test-negative, case-control analysis*

▪ Population: Children and adolescents aged 5–17 years and adults aged ≥18 years with ≥1 COVID-like 

symptom and nucleic acid amplification testing (NAAT)

▪ Exclusion criteria: Excluded individuals <4 months from last monovalent dose and individuals with 

immunocompromising conditions

▪ Periods for analysis:

• Tested: December 1, 2022 – February 13, 2023**

• Includes periods of both BA.5-related sublineage and XBB/XBB.1.5 sublineage predominance

ICATT: RelativeVE of bivalent booster against symptomatic infection in 

children and adolescents aged 5–17 years and adults aged ≥18 years

*Models adjusted for: age, gender, race, ethnicity, social vulnerability index and HHS region of the testing location, underlying conditions (presence versus absence), local incidence (cases per 100,000 by individual county and 

state in the 7 days before test date), and date of testing

**Analysis is an update of data published in Link-Gelles R, Ciesla AA, Roper LE, et al. Early estimates of bivalent mRNA booster dose vaccine effectiveness in preventing symptomatic SARS-CoV-2 infection attributable to SARS-CoV2 Omicron BA.5-related and XBB/XBB.1.5-related sublineages among immunocompetent adults—Increasing Community Access to Testing Program, United States, December 2022–January 2023. MMWR Morb Mortal Wkly Rep 

2023;72. https://www.cdc.gov/mmwr/volumes/72/wr/mm7205e2.htm

31
32

ICATT: RelativeVE of bivalent booster against symptomatic infection in children and 

adolescents aged 5–17 years, December 1, 2022 – February 13, 2023*

*Unpublished CDC data. 

Age group, years/mRNA Dosage Pattern

Total

tests

SARS-CoV-2 positive tests, Adjusted VE

N (row %) (95% CI)

5-11 years (authorized for bivalent booster 

on October 12, 2022)

Received 2-3 monovalent doses only (Ref) 4,855 1,433 (30) Ref

2 weeks-1 month since bivalent booster 600 73 (12) 65 (55 to 73)

2-3 months since bivalent booster 881 139 (16) 54 (43 to 62)

4-5 months since bivalent booster 58 10 (17) ----

12-17 years (authorized for bivalent booster 

on September 1, 2022)

Received 2-3 monovalent doses only (Ref) 8,243 3,194 (39) Ref

2 weeks-1 month since bivalent booster 443 73 (16) 68 (58 to 75)

2-3 months since bivalent booster 1,122 230 (20) 56 (49 to 62)

4-5 months since bivalent booster 283 68 (24) 53 (37 to 64)

0 20 40 60 80 100

Vaccine Effectiveness %
33

ICATT: Relative VE of bivalent booster against symptomatic infection in adults aged 

≥18 years, December 1, 2022 – February 13, 2023*

*Unpublished CDC data. 

33

Age group, years/mRNA Dosage Pattern Total

tests

SARS-CoV-2 

positive tests, Adjusted VE

N (row %) (95% CI)

18-49 years

Received 2-3 monovalent doses only (Ref) 182,741 82,043 (45) Ref

2 weeks-1 month since bivalent booster 10,758 3,127 (29) 51 (49 to 53)

2-3 months since bivalent booster 32,577 10,206 (31) 45 (43 to 46)

4-5 months since bivalent booster 9,197 2,882 (31) 41 (38 to 44)

50-64 years

Received 2-4 monovalent doses only (Ref) 60,822 31,878 (52) Ref

2 weeks-1 month since bivalent booster 6,223 2,331 (37) 46 (43 to 49)

2-3 months since bivalent booster 18,399 7,898 (43) 32 (29 to 34)

4-5 months since bivalent booster 4,837 2,030 (42) 28 (23 to 32)

≥65 years

Received 2-4 monovalent doses only (Ref) 28,307 14,246 (50) Ref

2 weeks-1 month since bivalent booster 4,579 1,788 (39) 38 (34 to 42)

2-3 months since bivalent booster 19,071 8,080 (42) 27 (25 to 30)

4-5 months since bivalent booster 5,796 2,431 (42) 21 (16 to 26)

0 20 40 60 80 100

Vaccine Effectiveness %