Effectiveness of a fourth dose of covid-19 mRNA vaccine against the omicron variant among long term care residents in Ontario, Canada: test negative design study.

ABSTRACT:

Objectives

To estimate the marginal effectiveness of a fourth versus third dose and the vaccine effectiveness of mRNA covid-19 vaccines BNT162b2 and mRNA-1273 against any infection, symptomatic infection, and severe outcomes (hospital admission or death) related to the omicron variant.

Design

Test negative design.

Setting

Long term care facilities in Ontario, Canada, 30 December 2021 to 27 April 2022.

Participants

After exclusions, 61 344 residents aged 60 years or older across 626 long term care facilities in Ontario, Canada who were tested for SARS-CoV-2 were included.

Main outcome measures

Laboratory confirmed omicron SARS-CoV-2 infection (any and symptomatic) by reverse transcription polymerase chain reaction (RT-PCR), and hospital admission or death

SUBMITTER: Grewal R 

PROVIDER: S-EPMC9257064 | biostudies-literature | 2022 Jul

REPOSITORIES: biostudies-literature