Journal-based CME Course: Association of Receiving a Fourth Dose of the BNT162b Vaccine With SARS-CoV-2 Infection Among Health Care Workers in Israel

Activity ID

9944

Expires

August 8, 2025

Format Type

Journal-based

CME Credit

1

Fee

$30

CME Provider: JAMA Network Open

Description of CME Course

Importance  Despite the high 3-dose vaccination rate among health care workers (HCWs) in Israel, a high rate of SARS-CoV-2 breakthrough infections in this group was observed during the Omicron wave. As a result, the Israeli Ministry of Health decided to recommend a fourth vaccine dose to medical staff.

Objective  To evaluate the benefit of a fourth BNT162b2 vaccine dose on the breakthrough infection rate among HCWs.

Design, Setting, and Participants  This multicenter cohort study was performed in January 2022, the first month of the 4-dose vaccination campaign, during a surge of the Omicron variant wave. All health care workers at 11 general hospitals in Israel who had been vaccinated with 3 doses up to September 30, 2021, and had not contracted COVID-19 before the vaccination campaign were included.

Exposures  Vaccination with a fourth dose of the BNT162b2 vaccine during January 2022.

Main Outcomes and Measures  Breakthrough COVID-19 infections in 4-dose recipients vs 3-dose recipients measured by a polymerase chain reaction test result positive for SARS-CoV-2. Health care workers were tested based on symptoms or exposure.

Results  A total of 29 611 Israeli HCWs (19 381 [65%] female; mean [SD] age, 44 [12] years) had received 3 vaccine doses between August and September 2021; of these, 5331 (18%) received the fourth dose in January 2022 and were not infected by the first week after vaccination. Overall breakthrough infection rates were 368 of 5331 (7%) in the 4-dose group and 4802 of 24280 (20%) in the 3-dose group (relative risk, 0.35; 95% CI, 0.32-0.39). Similar reductions were found in a matched analysis by the exact day of receiving the third vaccine (relative risk, 0.61; 95% CI, 0.54-0.71) and in a time-dependent Cox proportional hazards regression model (adjusted hazard ratio, 0.56; 95% CI, 0.50-0.63). In both groups, no severe disease or death occurred.

Conclusions and Relevance  In this cohort study, the fourth BNT162b2 vaccine dose resulted in a reduced breakthrough infection rate among hospital staff. This reduction was lower than that observed after the third dose; nevertheless, considering the high infectivity of the Omicron variant, which led to critical medical staff shortages, a fourth vaccine dose should be considered to mitigate the infection rate among HCWs.

Disclaimers

1. This activity is accredited by the American Medical Association.
2. This activity is free to AMA members.

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