Association of Receiving a Fourth Dose of the BNT162b Vaccine With SARS-CoV-2 Infection Among Health Care Workers in Israel.

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.

Utilization of the Public Health Ordinance to prevent nosocomial spread in a case of acute measles-associated psychosis.

Measles is a highly contagious disease. A 24 years old patient, recently exposed to measles (unvaccinated), presented in the emergency department with severe agitation, compatible with an acute psychotic episode, during the measles epidemic which spread in Israel in 2018-2019. Upon hospital admission, strict isolation was instructed, yet, without compliance, probably due to the patient's status. Measles diagnosis was promptly confirmed. As measles transmission was eminent, public health measures were employed through immediate implementation of the section 15 of the Public Health Ordinance, allowing for compulsory short-term isolation. The patient's condition improved within a few days and the measures were no longer necessary. This measles case occurred in the pre-Coronavirus disease 2019 (COVID-19) epidemic when use of a Public Health Ordinance was considered an extreme measure. This is in contrast to the current global use of Public Health laws to enforce strict quarantine and isolation on persons infected or potentially exposed to COVID-19. Nevertheless, minimizing infectious diseases transmission is a core function of public health law. Utilizing legal enforcement in circumstances of immediate public health hazard, such as nosocomial measles transmission, necessitates careful consideration. The integrative clinical and public health approach and prompt measures employed in this exceptional case, led to prevention of further infection spread.