Abstract
Objectives: In August 2021, 6 months after mass vaccination of the Israeli population with the two-dose BNT162b2 mRNA vaccine, a surge of coronavirus disease 2019 infections, mostly from the delta variant, appeared also among the vaccinated. In response, the Israeli Ministry of Health initiated a booster (third dose) vaccination program. We assessed the protective effect of the third dose among health care workers (HCWs).
Methods: Infections with severe acute respiratory syndrome coronavirus 2 are monitored systematically among HCWs at the Hadassah tertiary care medical centre in Jerusalem, Israel. In this cohort, we included breakthrough infections, defined as those occurring >180 days since the second vaccine dose. The follow-up period lasted 120 days. We compared infection rates between HCWs who received the booster dose and those who received only the two-dose regimen.
Results: The rate of breakthrough infections among HCWs who received only the two-dose regimen was 21.4% (85 of 398). The rate in the boosted group was 0.7% (35/4973; relative risk 30, 95% CI 20-50). Those results were seen in all age groups.
Discussion: The significantly lower rate of breakthrough infections in boosted HCWs indicates substantial protection by a third vaccine dose.
Keywords: Booster; Breakthrough infection; Health care workers; SARS-CoV-2; Third dose; Vaccine.
【저자키워드】 SARS-CoV-2, Vaccine, health care workers, Breakthrough infection, booster, third dose, 【초록키워드】 coronavirus disease, Coronavirus disease 2019, coronavirus, vaccination, Health care, health care workers, variant, risk, severe acute respiratory syndrome Coronavirus, delta variant, Relative risk, vaccine dose, BNT162b2, Cohort, infections, HCWs, Health care worker, breakthrough infections, Breakthrough infection, infection rate, Care, booster dose, protective effect, BNT162b2 mRNA vaccine, dose, HCW, mass vaccination, acute respiratory syndrome, follow-up period, 95% CI, acute respiratory syndrome coronavirus, acute respiratory syndrome coronavirus 2, infection rates, all age groups, significantly lower, two-dose regimen, Ministry of Health, Jerusalem, defined, indicate, initiated, 【제목키워드】 BNT162b2 vaccine, Health, Care, cohort analysis,