Impact of B.1.351 (beta) SARS-CoV-2 variant on BNT162b2 mRNA vaccine effectiveness in long-term care facilities of eastern France: a retrospective cohort study (preprint)

ABSTRACT

Background We aimed to assess the effectiveness of the BNT162b2 mRNA vaccine against B.1.351 (beta) variant among residents of long-term care facilities (LCTFs) in eastern France. Methods We used routinely collected surveillance and COVID-19 vaccination data to conduct a retrospective cohort study of SARS-CoV-2 B.1.351 infection incidence and vaccine effectiveness among LCTFs residents in eastern France between 15 January and 19 May 2021. Data from secondary RT-PCR screening were used to identify B.1.351 variants. Findings Included in our analysis were 378 residents from five LCTFs 287 (76%) females, with median (IQR) age of 89 (83-92) years. Two B.1.351 outbreaks took place in LTCFs in which more than 70% of residents had received two doses of BNT162b2 mRNA vaccine, which included 11 cases of severe disease and six deaths among those who had received two doses. Vaccine effectiveness (95% CI) seven days after the second dose of vaccine was 49% (14-69) against any infection with B.1.351 and 86% (67-94) against severe forms of COVID-19. In multivariable analysis, females were less likely to develop severe forms of disease (IRR = 0.35, 95% CI = 0.20-0.63). Interpretation We observed reduced vaccine effectiveness associated with B.1.351, as well as B.1.351 outbreaks in two LTCFs among individuals who had received two doses of vaccine. Our findings highlight the need to maintain SARS-CoV-2 surveillance in these high-risk settings beyond the current COVID-19 mass vaccination campaign, and advocate for a booster vaccine dose prior to the next winter season.