Early rate reductions of SARS-CoV-2 infection and COVID-19 in BNT162b2 vaccine recipients

Letter describes retrospective analysis of 9109 healthcare workers (HCW) in Israel, which found substantial early reductions in symptomatic COVID-19 rates following first vaccine dose (e.g. 1.2 per 10 000 person-days on days 15–28 vs 5.0 per 10 000 in unvaccinated HCWs).

SPS commentary:

There are a number of limitations to this research inherent to its observational design; in addition, there was no active laboratory surveillance so there may have been an underestimation of asymptomatic cases. The study was of healthcare workers only and the early rate reduction observed may differ from vaccine efficacy reported in the general population due to their higher exposure risk or due to exposure to more virulent or infectious strains. The findings require validation through further research.

The Lancet