THURSDAY, Dec. 9, 2021 (HealthDay News) — Rates of confirmed COVID-19 and severe illness as well as related mortality are lower among individuals who receive a booster dose following the two doses of the mRNA COVID-19 vaccine BNT162b2, according to two studies published online Dec. 8 in the New England Journal of Medicine.
Yinon M. Bar-On, from the Weizmann Institute of Science in Rehovot, Israel, and colleagues extracted data from July 30 to Oct. 10, 2021, for 4,696,865 persons aged 16 years and older who had received two doses of BNT162b2 at least five months earlier. The rates of confirmed COVID-19, severe illness, and death were examined among those who received a booster dose at least 12 days earlier compared with those who did not receive a booster dose (primary analysis) and with those who received the booster three to seven days earlier (secondary analysis). The researchers found that the rate of confirmed infection was about 10-fold lower in the booster group in the primary analysis and lower by a factor of 4.9 to 10.8 in the secondary analysis. The rates of severe illness were lower in the booster group by a factor of 17.9 and 6.5, respectively, in the primary and secondary analyses for those ages 60 years or older and by 21.7 and 3.7, respectively, for those ages 40 to 59 years.
Ronen Arbel, Ph.D., from Clalit Health Services in Tel Aviv, Israel, and colleagues examined the effectiveness of a BNT162b2 booster for lowering mortality due to COVID-19. Data were included for 843,208 participants (ages 50 years or older) who met eligibility criteria, 90 percent of whom received the booster. The researchers found that the rate of death due to COVID-19 was 0.16 and 2.98 per 100,000 persons per day in the booster and nonbooster groups, respectively, with an adjusted hazard ratio for death due to COVID-19 of 0.10.
These data “will provide valuable guidance for decision making in other countries, as the risk-benefit balance of introducing a booster dose is assessed,” write the authors of an accompanying editorial.
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