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.

Studies for variant delta

See all studies

Trial Design Variant Participants Comparisons
Type Intervention 1 Intervention 2 Overall risk
of bias
Highest assessment
Full description


Andrews N, medRxiv, 2021

Full text
Commentary
Commentary
Test-negative Delta Adults aged 16 years or older living in England 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


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



Barda N, Lancet, 2021

Full text
(21)02249-2/fulltextCommentary
Cohort Delta Individuals, 16 years or older, that received the second vaccine dose at least 5 months ago in Israel RNA based vaccine BNT162b2 booster BNT162b2
Moderate
Details

Full description



Barlow R, medRxiv, 2021

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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, medRxiv, 2021

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Commentary
Test-negative Delta Adults members of an integrated health care system (KPSC) in the USA RNA based vaccine mRNA-1273 No vaccine
Moderate
Details

Full description



Bruxvoort K, SSRN, 2021

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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



Chadeau-Hyam M, medRxiv, 2021

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Commentary
Commentary
Cross-sectional Delta Random selection of adults volunteering to provide self-sampled throat and nose swabs in England 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


Chemaitelly H, N Eng J Med, 2021

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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



Cohn B, medRxiv, 2021

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Commentary
Commentary
Cohort Delta Adults aged 18 and older including elderly and co-morbidities in all states and territories of USA RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 Unvaccinated
Serious
Details
Non replicating viral vector Ad26.COV2.S Unvaccinated
Serious
Details


de Gier B, medRxiv, 2021

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Commentary
Commentary
Cohort Delta Adolescents and adults in the Netherlands RNA based vaccine mRNA-173 No vaccine
Serious
Details

Full description

Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details
Any COVID-19 vaccine BNT162b2 or ChAdOx1 or mRNA-1273 or Ad26.COV2.S No vaccine
Serious
Details
RNA based vaccine BNT162b2 No vaccine
Serious
Details
Non replicating viral vector Ad26.COV2.S No vaccine
Serious
Details


Elliott P, medRxiv, 2021

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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



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



Glatman-Freedman A, Emerg Infect Dis, 2021

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Commentary
Cohort Delta Adolescents 12–15 years of age with no history of COVID-19 in Israel RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description



Goldberg Y, medRxiv, 2021

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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



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

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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



Li N-X, Emerg Microbes Infec, 2021

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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



Lin D, medRxiv, 2021

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Commentary
Commentary
Cohort Delta Residents of North Carolina, USA RNA based vaccine BNT162b2 No vaccine
Serious
Details

Full description

Non replicating viral vector Ad26.COV2.S No vaccine
Serious
Details


Liu C, medRxiv, 2021

Full text
Commentary
Commentary
Cohort Delta Adults including elderly and co-morbidities with no history of COVID-19 in multiple centres in New York, USA RNA based vaccine BNT162b2 or mRNA-1273 No vaccine
Serious
Details

Full description



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


Manley HJ, medRxiv, 2021

ttps://www.medrxiv.org/content/10.1101/2021.09.24.21264081v1Commentary
Commentary
Cohort Delta Adult maintenance dialysis (home and in center) without known prior COVID-19 infection treated at Dialysis Clinic, Inc. in USA. Any COVID-19 vaccine BNT162b2 or mRNA-1273 or Ad26.COV2.S No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 mRNA-1273
Serious
Details
Non replicating viral vector Ad26.COV2.S mRNA-1273
Serious
Details


Marti-nez Baz I, Euro surveillance, 2021

Full text
Commentary
Cohort Delta Close contacts of COVID-19 cases from 1 April to 31 August 2021 in Navarre, Spain. 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
Non replicating viral vector Ad26.COV2.S No vaccine
Serious
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


Morgan JA, Obstet Gynecol, 2021

Full text
Commentary
Cohort Delta Pregnant women in Louisiana, USA Any COVID-19 vaccine BNT162b2 or mRNA-1273 or Ad26.COV2.S No vaccine
Serious
Details

Full description



Murugesan M, SSRN, 2021

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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
Serious
Details

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

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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


Nordstrom P, SSRN, 2021

Full text
Commentary
Commentary
Cohort Delta General population including co-morbidities in Sweden. 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
Heterologous 1 ChAdOx-1 + 1 BNT162b2 OR 1 mRNA-1273 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



Polinski J, medRxiv, 2021

Full text
Commentary
Commentary
Cohort Delta Adults including elderly and co-morbidities with no history of COVID-19 in multiple centres throughout the USA Non replicating viral vector Ad26.COV2.S No vaccine
Serious
Details

Full description

ISRCTN21086382

Pouwels K, Nat Med, 2021

Full text
Full text
Commentary
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

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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

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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


Ranzani OT, medRxiv, 2021

Full text
Test-negative Delta RT-PCR from adults residing in Mato-Grosso do Sul Non replicating viral vector Ad26.COV2.S No vaccine
Moderate
Details

Full description



Robles-Fontan M, medRxiv, 2021

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Commentary
Commentary
Cohort Delta General population of Puerto Rico aged 12 years and older RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 No vaccine
Serious
Details
Non replicating viral vector Ad26.COV2.S No vaccine
Serious
Details


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



Self WH, MMWR, 2021

Full text
Test-negative Delta Adults hospitalized with COVID-19 like illness without Immunocompromising conditions living in United States, RNA based vaccine mRNA-1273 No vaccine
Serious
Details

Full description

RNA based vaccine BNT162b2 No vaccine
Serious
Details
Non replicating viral vector Ad26.COV2.S No vaccine
Serious
Details


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


Singh C, Epidemiol Infect, 2021

Full text
Commentary
Case-control Delta Adults aged 45 and up in a single centre in India Any COVID-19 vaccine ChAdOx1-S or BBV152 No vaccine
Serious
Details

Full description

Non replicating viral vector ChAdOx1-S No vaccine
Serious
Details
Inactivated virus BBV152 No vaccine
Serious
Details


Skowronski DM, medRxiv, 2021

Full text
Commentary
Commentary
Test-negative Delta SARS-CoV-2 test-positive cases and test-negative controls 18 years and over residing in British Columbia, 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
Heterologous 1 ChAdOx-1 + 1 BNT162b2 OR 1 mRNA-1273 No vaccine
Serious
Details
Heterologous 1 BNT162b2 + 1 mRNA-1273 No vaccine
Serious
Details


Skowronski DM (2), medRxiv, 2021

Full text
Commentary
Commentary
Test-negative Delta SARS-CoV-2 test-positive cases and test-negative controls 18 years and over residing in Quebec, 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
Heterologous 1 ChAdOx-1 + 1 BNT162b2 OR 1 mRNA-1273 No vaccine
Serious
Details
Heterologous 1 BNT162b2 + 1 mRNA-1273 No vaccine
Serious
Details


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, MMWR, 2021

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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



Vaishya R, SSRN, 2021

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Commentary
Commentary
Cohort Delta Vaccinated healthcare workers in 43 hospitals in 24 Indian cities Non replicating viral vector ChAdOx1-S BBV152
Serious
Details

Full description