cdc.gov/coronavirus

COVID-19 Vaccine Effectiveness

during Omicron

Ruth Link-Gelles, PhD, MPH

LCDR, US Public Health Service

Program Lead, COVID-19 Vaccine Effectiveness

Epidemiology Task Force, CDC

ACIP

April 20, 2022
 Evidence organized by outcome

– Infection

– Emergency department/urgent care (ED/UC)

– Hospitalization

Organization of presentation

2
Vaccine effectiveness (VE) data for 

infection with Omicron
 Nationwide community-based drive-through COVID-19 testing via pharmacies

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

excluded those who did not report vaccination status

 Design: Test-negative, case-control analysis

 Population: Persons with ≥1 COVID-like symptom and nucleic acid 

amplification testing (NAAT)

 Adjusted for: – Calendar day, race, ethnicity, gender, site’s HHS region, site census tract’s social vulnerability index 

(SVI)

– Prior infection excluded

 Period:

– Tested December 26, 2021 – March 23, 2022

Increasing Community Access to Testing (ICATT) 

Partnership: VE analysis for symptomatic infection
Tests with 

vaccine 

regimen, no.

SARS-CoV-2

positive, (%)

Adjusted 

VE

(95% CI)

Unvaccinated 208,122 50 Ref.

J&J + J&J

0–1 months since booster 1,023 47 25 (15-34)

2–4 months since booster 2,513 42 30 (24-36)

J&J + mRNA

0–1 months since booster 3,607 31 60 (57-62)

2–4 months since booster 9,787 30 55 (53-57)

mRNA + mRNA + mRNA

0–1 months since booster 78,242 27 68 (67–69)

2–4 months since booster 207,276 27 63 (63-64)

Increasing Community Access to Testing (ICATT) Partnership, booster VE against 

symptomatic infection in adults ≥18 years during Omicron, Dec 26, 2021–Mar 23, 2022

Accorsi et al., preliminary unpublished data

0 20 40 60 80 100

VaccineEffectiveness (%)
 Pfizer-BioNTech, Moderna, or ChAdOx1-S primary series, Pfizer-BioNTech or 

Moderna booster

 VE was generally

comparable by Omicron

sublineage

Data from the UK: VE vs. symptomatic infection comparing 

Omicron sublineages (BA.1 vs BA.2) by time since booster

https://www.medrxiv.org/content/10.1101/2022.03.22.22272691v1.full.pdf 6
 VE looks different for recipients of J&J vaccine; lower overall vs. regimens 

that include at least 1 mRNA

 Evidence of slight waning against infection for 3 mRNA doses by 2-4 months 

after the last dose

 Early VE data from the UK show similar VE for BA.1 and BA.2 sublineages of 

Omicron variant

Overall summary of VE against infection

7
Vaccine effectiveness data for emergency 

department/urgent care (ED/UC) due to 

Omicron in the US
VISION Multi-State Network of Electronic Health Records

 Delta vs. Omicron determined by 

time when Omicron predominated 

in study site (mid-December 2021)

 VE adjusted by propensity to be 

vaccinated weights, calendar time, 

region, local virus circulation, and 

age

 Vaccination documented by 

electronic health records and state 

and city registries

 Cases: COVID-like illness (CLI) with positive 

PCR for SARS-CoV-2 within 14 days before or 

72 hours after the admission or encounter

 Controls: CLI with negative PCR for SARSCoV-2
VISION: mRNA VE for ED/UC visits by number of doses and time since last dose 

receipt for adults ≥50 years, Dec 2021–Mar 2022, by immunocompromised status

CDC, preliminary unpublished data. Individuals with prior infections excluded. Logistic regression conditioned on calendar week and geographic area, and adjusted for age, 

sex, race, ethnicity, local virus circulation, respiratory or nonrespiratory underlying medical conditions, and propensity to be vaccinated 10

Adjusted VE% (95% CI)

Status: Immunocompromised Not immunocompromised

2 doses

14-59 days 79 (25-94) 74 (66-81)

60-119 days 18 (-25-49) 59 (66-81)

120-179 days 46 (18-65) 51 (45-56)

180-239 days 48 (22-65) 43 (37-48)

240-299 days 48 (33-60) 49 (45-52)

300+ days 45 (29-58) 53 (49-56)

3 doses

14-59 days 85 (78-90) 88 (87-89)

60-119 days 72 (64-78) 85 (84-86)

120-179 days 48 (32-60) 75 (72-78)

180-239 days 50 (-49-87) 77 (53-89)

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

Vaccine Effectiveness (%)

Immunocompromised Not immunocompromised
Vaccine effectiveness data for 

hospitalization due to Omicron in the US
VISION: mRNA VE for hospitalization by number of doses and time since last dose 

receipt for adults ≥50 years, Dec 2021–Mar 2022, by immunocompromised status

CDC, preliminary unpublished data. Individuals with prior infections excluded. Logistic regression conditioned on calendar week and geographic area, and adjusted for age, 

sex, race, ethnicity, local virus circulation, respiratory or nonrespiratory underlying medical conditions, and propensity to be vaccinated 12

Adjusted VE% (95% CI)

Status: Immunocompromised Not immunocompromised

2 doses

14-59 days 38 (-25-71) 81 (70-88)

60-119 days 27 (-7-51) 74 (66-80)

120-179 days 33 (6-52) 64 (56-71)

180-239 days 35 (13-51) 60 (53-61)

240-299 days 39 (27-50) 57 (53-61)

300+ days 42 (29-52) 66 (62-69)

3 doses

14-59 days 81 (75-85) 93 (91-94)

60-119 days 74 (68-78) 91 (90-92)

120-179 days 49 (37-58) 84 (81-87)

-40 -20 0 20 40 60 80 100

Vaccine Effectiveness (%)

Immunocompromised Not immunocompromised
VE against COVID-19-associated hospitalizations

during Omicron, Dec 16, 2021-Mar 7, 2022

• VE of any booster dose is significantly higher than VE for 1 Janssen dose only

• VE of 3 mRNA doses is significantly higher than Janssen plus booster

Natarajan K, Prasad N, Dascomb K, et al. Effectiveness of Homologous and Heterologous COVID-19 Booster Doses Following 1 Ad.26.COV2.S (Janssen [Johnson & Johnson]) Vaccine Dose Against 

COVID-19–Associated Emergency Department and Urgent Care Encounters and Hospitalizations Among Adults — VISION Network, 10 States, December 2021–March 2022. MMWR Morb Mortal Wkly

Rep. ePub: 29 March 2022. DOI: http://dx.doi.org/10.15585/mmwr.mm7113e2external icon
Effectiveness of mRNA vaccines for preventing 

COVID-19 hospitalization, IVY Network

Tenforde MW, Self WH, Naioti EA, et al. Sustained Effectiveness of Pfizer-BioNTech and Moderna Vaccines Against COVID-19 Associated Hospitalizations Among Adults — United States, 

March–July 2021. MMWR Morb Mortal Wkly Rep 2021;70:1156-1162. DOI: http://dx.doi.org/10.15585/mmwr.mm7034e2

 Population: Adults (≥18 years) hospitalized at

21 medical centers in 18 states

 Design: Test-negative case-control

 Case status:

– Cases: COVID-like illness and

SARS-CoV-2/RT-PCR (+)

– Controls: COVID-like illness and SARS-CoV-2 RT-PCR (-)

 Testing: SARS-CoV-2 testing within 10 days of illness onset, and admission 

within 14 days of illness onset
Effectiveness of mRNA COVID-19 vaccines against COVID-19-

associated hospitalization, Dec 26, 2021 – Mar 15, 2022

Group No. of vaccinated 

case-patients/total 

case-patients 

(%)

No. of vaccinated 

control-patients/ total 

control-patients 

(%)

Adjusted* vaccine 

effectiveness

% (95% CI)

3 doses overall 288/909 (32) 508/776 (65) 78 (73–83)

Immunocompromised 153/250 (61) 191/238 (80) 65 (44–78)

7–120 days 89/186 (48) 134/181 (74) 73 (55–84)

>120 days 64/161 (40) 57/104 (55) 54 (16–75)

Not immunocompromised 135/659 (20) 317/538 (59) 85 (80–89)

7–120 days 118/642 (18) 273/494 (55) 86 (81–89)

>120 days 17/541 (3) 44/265 (17) 79 (59–89)

*Adjusted for age (18-64 or ≥65 years), sex, race/ethnicity, admission date (biweekly), and US census region

CDC preliminary unpublished data
IVY: VE against invasive mechanical ventilation or inhospital death, by variant, Jul 4, 2021–Jan 24, 2022 

Tenforde MW, Self WH, Gaglani M, et al. Effectiveness of mRNA Vaccination in Preventing COVID-19–Associated Invasive Mechanical Ventilation and Death — United States, March 2021–

January 2022. MMWR Morb Mortal Wkly Rep 2022;71:459–465. DOI: http://dx.doi.org/10.15585/mmwr.mm7112e1 16

No. vaccinated

cases/

Total no.

case (%)

No. vaccinated

controls/

Total no.

controls (%)

Adjusted

VE

% (95% CI)

Pre-Delta, 2 doses 13/259 (5.0) 893/1,738 (51.4) 95 (90–97)

Delta 235/1,027 (22.9) 2,741/3,865 (70.9) 89 (87–91)

2 doses, median 159 days after dose 2 218/1,010 (21.6) 2,402/3,526 (68.1) 88 (86–90)

3 doses, median 35 days after dose 3 17/809 (2.1) 339/1,463 (23.2) 95 (91–97)

Omicron 59/154 (38.3) 396/501 (77.0) 86 (79–91)

2 doses, median 256 days after dose 2 46/141 (32.6) 193/308 (62.7) 79 (66–87)

3 doses, median 60 days after dose 3 13/108 (12.0) 193/308 (62.7) 94 (88–97)

0 20 40 60 80 100

VaccineEffectiveness (%)
Summary
2-dose 3-dose

Adjusted VE Adjusted VE

% (95% CI) % (95% CI)

Infection

1mo post-last dose, ICATT 28 (15-40) 65 (62-68)

3mos post-last dose, ICATT 11 (3-19) --

Emergency

department/

urgent care

Last dose <59 days ago, VISION 74 (66-81)* 88 (87-89)*

Last dose 120-179 days ago, VISION 51 (45-56)* 75 (72-78)*

Hospitalization

Last dose <59 days ago, VISION 81 (70-88)* 93 (91-94)*

Last dose 120-179 days ago, VISION 64 (56-71)* 84 (81-87)*

3rd dose 7-120 days ago, IVY Not estimated 86 (81-89)**

3rd dose >120 days ago, IVY Not estimated 79 (59-89)**

Critical 

illness/death

2

nd dose median 256 days/3rd dose 

median 60 days ago, IVY

79 (66-87) 94 (88-97)

Summary: VE of 2 doses of mRNA vaccine increases with increasing severity of 

outcome during Omicron in adults ≥18 years; 3rd dose increases VE

18

Booster receipt increases protection across all outcomes.

Booster dose VE remains high among non-immunocompromised individuals 4-6 months after dose.

*Among non-immunocompromised individuals ≥50 years of age. ** Among non-immunocompromised individuals ≥18 years of age.

0 20 40 60 80 100

VaccineEffectiveness (%)

2-dose 3-dose
Not immunocompromised Immunocompromised

2-dose VE against:

Infection (+/- symptoms) Limited protection, fast waning Not estimated

ED/UC Higher protection, some waning Not estimated

Hospitalization Highest protection, some waning Not estimated

3-dose VE against:

Infection (+/- symptoms) Some protection, evidence of waning Not estimated

ED/UC Some protection, limited waning Some protection, clear waning

Hospitalization Highest protection, limited waning Highest protection, clear waning

Summary: mRNA VE during Omicron

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 Tamara Pilishvili

 Sara Oliver

 Aron Hall

 Adam MacNeil

 Sarah Meyer

 Minal Patel

 Site PIs and study staff for IVY, 

VISION, and ICATT

– Emma Accorsi

– Amadea Britton

– Jill Ferdinands

– Katherine Fleming-Dutra

– Manish Patel

– Namrata Prasad

– Diya Surie

– Mark Tenforde

– Mark Thompson

Acknowledgements

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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.