Effectiveness of BNT162b2 Vaccine Booster against SARS-CoV-2 Infection and Breakthrough Complications, Israel
Aharona Glatman‐Freedman, Michal Bromberg, Yael Hershkovitz, Hanna Sefty, Zalman Kaufman, Rita Dichtiar, Lital Keinan‐Boker
Abstract
T he mass severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) BNT162b2 (Pfizer-BioNTech, https://www.pfizer.com) vaccination campaign in Israel was associated with a decline in the number of SARS-CoV-2 infections, hospitalizations, and deaths, reaching a nadir by mid-May 2021 (1). However, beginning the third week of June 2021, a new rise in the number of SARS-CoV-2 cases was observed, including cases among fully vaccinated persons (1,2). Waning humoral immune response after the second vaccine dose was then found to be associated with increased incidence of SARS-CoV-2related infections, hospitalizations, and deaths caused primarily by the B.1.617.2 (Delta) variant (3). In response to the increasing illness and deaths, the Israel Ministry of Health (MOH) recommended a third (booster) BNT162b2 vaccine dose for persons for whom at least 5 months had passed after receiving the second vaccine dose (4). The elderly and other high-risk groups were prioritized at first (4), and other age groups were added rapidly thereafter (5). We estimated the booster dose vaccine effectiveness (VE) against SARS-CoV-2 infection and the rate reduction of complications in breakthrough coronavirus disease (COVID-19) cases after the BNT162b2 booster dose in persons >16 years of age, by age group, for up to 20 weeks after receipt of the booster dose.