COVID-19 vaccine effectiveness on variants of concern

Observational studies

Protocol

Our protocol is available on Zenodo here .

Variants of concern

We identified observational studies assessing vaccine effectiveness on variant from the studies identified by Krause P et al. Lancet 2021 and the process described in our protocol .

Vaccine effectiveness is based on direct evidence but also indirect evidence (i.e., variant exposure extrapolated the prevalence of the variant in the population) reported in the manuscript or in secondary sources.

Risk of bias assessment is ongoing and may be missing on the forest plots.

Description of primary studies

In this table, we report the main characteristics of the Non randomized studies identified. The risk of bias by domain as well as overall risk of bias reported in the table corresponds to the highest risk of bias for the outcomes assessed for the systematic review.
Trial Design Variant Participants Comparisons
Type Intervention 1 Intervention 2 Overall risk
of bias
Highest assessment
Full description


Bajema K, MMWR, 2021

Full text
Commentary
Test-negative Delta U.S. veterans hospitalized at five Veterans Affairs Medical Centers (VAMCs) in USA. RNA based vaccine mRNA-1273 No vaccine
Moderate
Details

Full description

RNA based vaccine BNT162b2 No vaccine
Moderate
Details
RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Moderate
Details


Bar-On Y, N Engl J Med, 2021

Full text
Commentary
Cohort Delta Israel residents 60 years of age or older who had been fully vaccinated at least 5 months earlier RNA based vaccine BNT162b2 booster BNT162b2
Serious
Details

Full description



Barlow R, medRxiv, 2021

Full text
Commentary
Commentary
Test-negative Delta Adults (15+ year old) twithout previous SARS-CoV-2 infection hat were tested for SARS-CoV-2 during July 2021 in a single county in USA. RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details
Non replicating viral vector Ad26.COV2.S No vaccine
Serious
Details


Bhattacharya A, Diabetes Metab Syndr, 2021

Full text
Commentary
Cohort Delta Adults attending a COVID-19 testing clinic and hospitalized COVID-19 patients in a single center in India Any COVID-19 vaccine ChAdOx1 or BBV152 No vaccine
Serious
Details

Full description



Bruxvoort K, SSRN, 2021

Full text
Commentary
Commentary
Cohort Delta Adults aged ≥18 years who are members of Kaiser Permanente Southern California in the USA RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

NCT04607941

Charmet T, Lancet Reg Health Eu, 2021

Full text
Commentary
Case-control Alpha Adults in France with or without prior history of infection (>2 months previous to index infection) RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description

NCT04607941

Charmet T, Lancet Reg Health Eu, 2021

Full text
Commentary
Case-control Beta/Gamma Adults in community with or without prior history of infection in France RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description



Chemaitelly H, medRxiv, 2021

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Commentary
Cohort Beta Immunosuppressed kidney transplant recipients in Qatar. RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Moderate
Details

Full description



Chemaitelly H, Nat. Med., 2021

Full text
Test-negative Alpha Mainly working-age adults not vaccinated or receiving at least one dose of the mRNA- 1273 vaccine or completed the two-dose regimen RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description



Chemaitelly H, N Eng J Med, 2021

Full text
Commentary
Test-negative Beta Adults and children with PCR-confirmed/negative SARS-CoV-2 in Qatar. RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description



Chemaitelly H, N Eng J Med, 2021

Full text
Commentary
Test-negative Alpha Adults and children with PCR-confirmed/negative SARS-CoV-2 in Qatar. RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description



Chemaitelly H, Nat. Med., 2021

Full text
Test-negative Beta Mainly working-age adults not vaccinated or receiving at least one dose of the mRNA- 1273 vaccine or completed the two-dose regimen RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description



Chemaitelly H, N Eng J Med, 2021

Full text
Commentary
Test-negative Delta Adults and children with PCR-confirmed/negative SARS-CoV-2 in Qatar. RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description



Chung H, BMJ, 2021

Full text
Commentary
Commentary
Commentary
Test-negative Alpha People with COVID-like symptoms and with no history of COVID-19 tested for SARS-CoV-2 RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Moderate
Details

Full description



Chung H, BMJ, 2021

Full text
Commentary
Commentary
Commentary
Test-negative Beta/gamma People with COVID-like symptoms and with no history of COVID-19 tested for SARS-CoV-2 RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Moderate
Details

Full description



Corchado-Garcia J, medRxiv, 2021

Full text
Commentary
Cohort Delta Adults who underwent SARS-CoV-2 polymerase chain reaction (PCR) testing in multiple centers in USA Non replicating viral vector Ad26.COV2.S No vaccine
Serious
Details

Full description



Dagan N, Nat Med, 2021

Full text
Commentary
Cohort Alpha Pregnant women, aged 16 years or older, in Israel RNA based vaccine BNT162b2 No vaccine
Moderate
Details

Full description



Dagan N, N Engl J Med, 2021

Full text
Commentary
Cohort Alpha Individuals 16 years and older with no previous documented infection with SARS-CoV-2 (PCR) in Israel RNA based vaccine BNT162b2 No vaccine
Moderate
Details

Full description



Elliott P, medRxiv, 2021

Full text
Commentary
Commentary
Cross-sectional Delta Adults aged 18 to 64 years In England, UK. Any COVID-19 vaccine BNT162b2 or mRNA-1273 or ChAdOx1-S No vaccine
Serious
Details

Full description



Flacco M, Vaccines, 2021

mdpi.com/2076-393X/9/6/628Commentary
Cohort Alpha Adults aged 18 and up without previous SARS-CoV-2 infection residing in Pescara, Italy RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details
Any COVID-19 vaccine BNT162b2 or mRNA-1273 or ChAdOx1-S No vaccine
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details


Fowlkes A, MMWR, 2021

Full text
Cohort Delta Adults with occupation involving regular direct contact (within three feet) with others, ) Any COVID-19 vaccine BNT162b2 or mRNA-1273 or Ad26.COV2.S No vaccine
Moderate
Details

Full description



Giansante C, Acta Biomed, 2021
New

Full text
Commentary
Cohort Alpha The staff of the Bologna Health Trust, Emilia Romagna Region, Northern Italy. RNA based vaccine BNT162b2 or mRNA-1273 No vaccine Extraction in progress

Full description



Glampson B, medRxiv, 2021
New

Full text
Commentary
Cohort Alpha Adults (16 years and older) eligible to be offered a COVID-19 in the UK. Non replicating viral vector ChAdOx1-S No vaccine Extraction in progress

Full description

RNA based vaccine BNT162b2 No vaccine Extraction in progress


Goldberg Y, medRxiv, 2021

Full text
Commentary
Commentary
Cohort Delta Elderly ages 60 and up who became fully vaccinated between January 16-31, 2021 and without previous SARS-CoV-2 infection in multiple centres in Israel RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description



Grannis S, MMWR, 2021

Full text
Commentary
Test-negative Delta Adults hospitalized with COVID-19-like illness in 9 states in multiple centres in USA RNA based vaccine mRNA-1273 No vaccine
Moderate
Details

Full description

Any COVID-19 vaccine BNT162b2 or mRNA-1273 or Ad26.COV2.S No vaccine
Moderate
Details
RNA based vaccine BNT162b2 No vaccine
Moderate
Details
Non replicating viral vector Ad26.COV2.S No vaccine
Moderate
Details


Griffin J, MMWR, 2021

Full text
Commentary
Cohort Delta All aged 12 and up residents of Los Angeles County in multiple centres in USA Any COVID-19 vaccine BNT162b2 or mRNA-1273 or Ad26.COV2.S No vaccine
Critical
Details

Full description



Haas E, Lancet, 2021
New

Full text
Commentary
Cohort Alpha Adults (16 years and older) with no history of COVID-19 in Israel RNA based vaccine BNT162b2 No vaccine Extraction in progress

Full description



Hitchings M, Lancet Reg Health Am, 2021

Full text
Full text
Commentary
Commentary
Commentary
Test-negative Gamma All healthcare workers, including in hospitals, primary care, general, and specialized units Inactivated virus CoronaVac No vaccine
Moderate
Details

Full description

ISRCTN, number 39557.

Hyams C, Lancet Infect Dis, 2021

Full text
Commentary
Test-negative Alpha Adults >80 years who were admitted to hospital in two NHS trusts in Bristol, UK with signs and symptoms of respiratory disease(test-positive/negative) Non replicating viral vector ChAdOx1-S No vaccine
Moderate
Details

Full description

RNA based vaccine BNT162b2 No vaccine
Moderate
Details


Israeli Ministry of Health, *, 2021

Full text
Cohort Delta All residents aged 16 years and older in Israel RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description



Kang M, SSRN, 2021

Full text
Commentary
Commentary
Commentary
Cohort Delta Close contacts of confirmed COVID cases during an outbreak in China Inactivated virus HB02/WIV04/CoronaVac/BICV No vaccine
Serious
Details

Full description



Kim S, J Infect Dis, 2021
New

Full text
Commentary
Test-negative Alpha Adolescents and adults with COVID-like symptoms at 5 centers in the USA. RNA based vaccine BNT162b2 or mRNA-1273 No vaccine Extraction in progress

Full description



Layan M, medRxiv, 2021

Full text
Cohort Alpha Household members close contact of an HCW index case RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description



Lefevre B, medRxiv, 2021

Full text
Commentary
Cohort Beta Adults including elderly in 5 centres in France. RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description



Li N-X, Emerg Microbes Infec, 2021

Full text
Commentary
Test-negative Delta Adults aged 18-59 years undergoing PCR testing in China. Inactivated virus HB02 or WIV04 or CoronaVac No vaccine
Serious
Details

Full description



Lopez Bernal J, BMJ, 2021

Full text
Commentary
Commentary
Test-negative Alpha Adults aged 70 years and older who reported symptoms of COVID-19 Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 No vaccine
Serious
Details


Lopez J, N Engl J Med, 2021

Full text
Commentary
Test-negative Alpha Data on all symptomatic sequenced cases of COVID-19 in England Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details

Full description

Any COVID-19 vaccine BNT162b2 or ChAdOx1-S No vaccine
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details


Lopez J, N Engl J Med, 2021

Full text
Commentary
Test-negative Delta Data on all symptomatic sequenced cases of COVID-19 in England Non replicating viral vector ChAdOx1-S No vaccine
Moderate
Details

Full description

Any COVID-19 vaccine BNT162b2 or ChAdOx1-S No vaccine
Moderate
Details
RNA based vaccine BNT162b2 No vaccine
Moderate
Details


McKeigue P, medRxiv, 2021

Full text
Commentary
Commentary
Case-control Delta Population of Scotland Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details


McKeigue P, medRxiv, 2021

Full text
Commentary
Commentary
Case-control Alpha Population of Scotland Any COVID-19 vaccine BNT162b2 or mRNA-1273 or ChAdOx1-S No vaccine
Serious
Details

Full description



Murugesan M, SSRN, 2021

Full text
Commentary
Commentary
Cohort Delta Health care workers without previous COVID-19 infection at a single center in Vellore, India. Any COVID-19 vaccine ChAdOx1-S or BBV152 No vaccine Extraction in progress

Full description



Nanduri S, MMWR, 2021

Full text
Commentary
Cohort Delta Residents at 14,917 nursing homes in the USA RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details


Nasreen S, medRxiv, 2021

Full text
Commentary
Commentary
Commentary
Test-negative Beta/Gamma Symptomatic community-dwelling individuals aged ≥16 years with no history of SARS-CoV-2 infection in Ontario, Canada RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details


Nasreen S, medRxiv, 2021

Full text
Commentary
Commentary
Test-negative Alpha Symptomatic community-dwelling individuals aged ≥16 years with no history of SARS-CoV-2 infection in Canada RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details


Nasreen S, medRxiv, 2021

Full text
Commentary
Commentary
Test-negative Delta Symptomatic community-dwelling individuals aged ≥16 years with no history of SARS-CoV-2 infection in Canada RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details


Nunes B, medRxiv, 2021

Full text
Commentary
Commentary
Cohort Delta Older adults aged 65 to 79 without previous SARS-CoV-2 infection living in the community in mainland Portugal RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details

Full description



Patalon T, medRxiv, 2021

Full text
Commentary
Commentary
Test-negative Delta Aged 40 and up Maccabi Healthcare Services members in multiple centres in Israel RNA based vaccine BNT162b2 booster BNT162b2
Moderate
Details

Full description

ISRCTN21086382

Pouwels K, medRxiv, 2021

Full text
Commentary
Cohort Alpha Adults from households randomly selected across the UK. RNA based vaccine mRNA-1273 No vaccine
Moderate
Details

Full description

Non replicating viral vector ChAdOx1-S No vaccine
Moderate
Details
RNA based vaccine BNT162b2 No vaccine
Moderate
Details
ISRCTN21086382

Pouwels K, medRxiv, 2021

Full text
Commentary
Cohort Delta Adults from households randomly selected across the UK. RNA based vaccine mRNA-1273 No vaccine
Moderate
Details

Full description

Non replicating viral vector ChAdOx1-S No vaccine
Moderate
Details
RNA based vaccine BNT162b2 No vaccine
Moderate
Details


Pramod S, medRxiv, 2021

Full text
Commentary
Commentary
Test-negative Delta Health care workers at a single center in India Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details

Full description



Puranik A, medRxiv, 2021

Full text
Commentary
Commentary
Cohort Delta Adults who underwent SARS-CoV-2 polymerase chain reaction (PCR) testing in multiple centers in USA RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

RNA based vaccine mRNA-1273 BNT162b2
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details


Puranik A, medRxiv, 2021

Full text
Commentary
Commentary
Cohort Alpha Adults who underwent SARS-CoV-2 polymerase chain reaction (PCR) testing at the Mayo Clinic and hospitals affiliated with the Mayo Clinic Health S RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

RNA based vaccine mRNA-1273 BNT162b2
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details


Ranzani O, medRxiv, 2021

Full text
Commentary
Commentary
Test-negative Gamma Adults ≥70 years of age, residents of São Paulo State and who underwent SARS-CoV-2 RT-PCR testing in multiple centers in Brazil Inactivated virus CoronaVac No vaccine
Serious
Details

Full description



Rosenberg E, MMWR, 2021

Full text
Full text
Commentary
Cohort Delta Adults aged ≥18 years residing in New York state in multiple centres in USA Any COVID-19 vaccine BNT162b2 or mRNA-1273 or Ad26.COV2.S No vaccine
Serious
Details

Full description



Seppala E, Euro Surveill, 2021

Full text
Commentary
Cohort Alpha All adults aged 18 years or older with no prior SARS-CoV-2 infection with a national identification number registered in multiple centres in Norway RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details

Full description



Seppala E, Euro Surveill, 2021

Full text
Commentary
Cohort Delta All adults aged 18 years or older with no prior SARS-CoV-2 infection with a national identification number registered in multiple centres in Norway RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details

Full description



Sheikh A, Lancet, 2021

Full text
Commentary
Test-negative Delta People of all ages tested for COVID-19 by RT-PCR in Scotland Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 No vaccine
Serious
Details


Sheikh A, Lancet, 2021

Full text
Commentary
Test-negative Alpha People of all ages tested for COVID-19 by RT-PCR in Scotland Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 No vaccine
Serious
Details


Skowronski D, Clin Infect Dis, 2021

Full text
Commentary
Commentary
Test-negative Alpha Elderly aged 70 and older in communities in British Colombia, Canada RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details

Full description



Skowronski D, Clin Infect Dis, 2021

Full text
Commentary
Commentary
Test-negative Gamma Elderly aged 70 and older in communities in British Colombia, Canada RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details

Full description



Stowe J, PHE Publishing, 2021

Full text
Commentary
Test-negative Delta Symptomatic COVID-19 patients Non replicating viral vector ChAdOx1-S No vaccine
Moderate
Details

Full description

Any COVID-19 vaccine BNT162b2 or ChAdOx1-S No vaccine
Moderate
Details
RNA based vaccine BNT162b2 No vaccine
Moderate
Details


Tang P, medRxiv, 2021

Full text
Commentary
Commentary
Test-negative Delta Resident population in multiple centres in Qatar RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details
NCT04848584

Tartof S, Lancet, 2021

Full text
(21)02183-8/fulltext; Full text
Commentary
Commentary
Commentary
Cohort Delta Kaiser Permanente Southern California healthcare system members aged 12 and up in multiple centres in USA RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description



Tenforde M, Clin Infect Dis, 2021

Full text
Commentary
Commentary
Test-negative Alpha Hospitalized adults at 18 centers in the USA. RNA based vaccine mRNA-1273 No vaccine Extraction in progress

Full description

RNA based vaccine BNT162b2 or mRNA-1273 No vaccine Extraction in progress
RNA based vaccine BNT162b2 No vaccine Extraction in progress


Tenforde M, MMWR, 2021

Full text
Commentary
Cohort Alpha Hospitalized adults at 21 centers in the USA RNA based vaccine BNT162b2 or mRNA-1273 No vaccine Extraction in progress

Full description



Tenforde M, MMWR, 2021

Full text
Commentary
Cohort Delta Hospitalized adults at 21 centers in the USA RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details

Full description



Thiruvengadam R, SSRN, 2021

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Commentary
Commentary
Test-negative Delta Individuals attending for RT-PCR testing for suspected SARS-CoV-2 infection at 2 centers in India Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details

Full description



Thompson M, N Engl J Med, 2021

Full text
Commentary
Commentary
Test-negative Delta Adults ≥50 years with Covid-19–like illness at multiple sites in the USA RNA based vaccine mRNA-1273 No vaccine
Moderate
Details

Full description

RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Moderate
Details
RNA based vaccine BNT162b2 No vaccine
Moderate
Details
Non replicating viral vector Ad26.COV2.S No vaccine
Moderate
Details


Vaishya R, SSRN, 2021

Full text
Commentary
Commentary
Cohort Delta Vaccinated healthcare workers in 43 hospitals in 24 Indian cities Non replicating viral vector ChAdOx1-S Whole-Virion Inactivated Vero Cell (BBV152)
Serious
Details

Full description



Yassi A, PLoS ONE, 2021

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Commentary
Commentary
Cohort Gamma Healthcare workers in Vancouver, Canada RNA based vaccine BNT162b2 or mRNA-1273 No vaccine Extraction in progress

Full description