Early rate reductions of SARS-CoV-2 infection and COVID-19 in BNT162b2 vaccine recipients
In December, 2020, the Israeli Government approved the BNT162b2 COVID-19 vaccine and initiated a national immunisation campaign prioritising health-care workers (HCWs), as in other countries.1 This campaign coincided with a third wave of COVID-19, peaking at 10 116 daily new cases by mid-January, 2021. The Sheba Medical Center, Israel’s largest hospital with 9647 HCWs, began staff vaccination on Dec 19, 2020. All HCWs, excluding those with previous SARS-CoV-2 infection, were eligible for vaccination. Clinical trial data of BNT162b2 vaccine estimated an early vaccine efficacy in preventing COVID-19 of 52·4% before dose two, and 90.5% on days 2–7 after dose two.2 A recent analysis of BNT162b2 vaccine data estimated vaccine efficacy of 89–91% during days 15–28 after the first dose.3 We examined early reductions in SARS-CoV-2 infection and COVID-19 rates in vaccinated HCWs. To assess vaccine-associated rate reductions we analysed a retrospective cohort of 9109 vaccine-eligible HCWs, comparing vaccinated versus unvaccinated. Active daily symptom reporting and immediate sameday testing allowed for prompt (<24h) detection and investigation of exposed or symptomatic HCWs.4 We defined all HCWs with positive SARS-CoV-2 PCR at Sheba Medical Center or in the community as cases of SARS-CoV-2 infection. All SARS-CoV-2-infected HCWs were contacted by infection control staff and requested to respond to a contact tracing questionnaire and a clinical questionnaire specifically regarding COVID-19 symptoms. Symptomatic HCWs were defined as COVID-19 cases.