Abstract
BACKGROUND: The rapid vaccination campaign against COVID-19 in Israel relied on the BNT162b2 vaccine. We performed a longitudinal analysis of multiple cohorts, using individual data, to evaluate the effectiveness of the vaccine against new and breakthrough cases. METHODS: We estimated vaccine effectiveness (VE) for 27 consecutive cohorts, each comprised of individuals vaccinated on specific days. VE against new COVID-19 cases was evaluated for five SARS-CoV-2-related outcomes: infection, symptomatic disease, hospitalisation, severe/critical disease and death. For breakthrough cases, rate reduction was evaluated for hospitalisation, severe/critical disease and death. Outcomes were evaluated at predetermined time-periods after vaccination, the last one dedicated to individuals who became SARS-CoV-2-positive 22-28 days after the second dose. FINDINGS: The highest VE estimates against new cases in ≥16 year old individuals, for all outcomes, were reached at the 15-21 day period after the second dose, ranging between 97.7% (95% CI: 95.9-98.7%) for deaths and 98.6% (95% CI: 97.8-99.1%) for severe/critical disease. VE estimates of the 14-20 day period after the first dose ranged between 54.3% (95% CI: 50.6-57.8%) for infection and 77.3% (95% CI: 71.2-82.1%) for severe/critical disease. VE rose more slowly among ≥80 year old individuals. Rate reductions of breakthrough complications were highest at the 22-28 day period after the second dose, ranging between 47.4% (95% CI: 4.3-71.2%) for death and 66.2% (95% CI: 44.2-79.6%) for severe/critical disease. INTERPRETATION: The BNT162 vaccine is highly effective in preventing new SARS-CoV-2 cases. Among ≥80 year old individuals, high effectiveness develops more slowly. In breakthrough cases, vaccination reduces complications and death. FUNDING: None.