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.

Analyses for variant delta and Beta were updated, some studies are awaiting classification ( last search date 24 sep, 2021).

Analyses for other variants of concern are not up to date; data extraction is in process.

Studies for variant gamma

See all studies

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


Hitchings M, medRxiv, 2021

Full text
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



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