HealthDay News — A fourth dose of the BNT162b2 vaccine is effective for reducing the risk for COVID-19-related outcomes in the short term, according to a study published online April 13 in the New England Journal of Medicine.

Ori Magen, MD, from the Clalit Research Institute in Tel Aviv, Israel, and colleagues used data recorded by the largest health care organization in Israel from January 3 to February 18, 2022, to examine the early effectiveness of a fourth dose of the BNT162b2 vaccine for prevention of COVID-19-related outcomes. The primary analysis included 182,122 pairs aged 60 years or older, who had and had not received a fourth dose, individually matched for multiple sociodemographic and clinical variables.

The researchers found that during days 7 to 30 after the fourth dose, the relative vaccine effectiveness was estimated to be 45, 55, 68, 62, and 74% against polymerase chain reaction-confirmed SARS-CoV-2 infection, symptomatic COVID-19, COVID-19-related hospitalization, severe COVID-19, and COVID-19-related death, respectively. The corresponding estimates were 52, 61, 72, 64, and 76% during days 14 to 30 after the fourth dose. For COVID-19-related hospitalization and for severe COVID-19, the difference in absolute risk (three versus four doses) during days 7 to 30 after a fourth vaccine dose was 180.1 and 68.8 cases per 100,000 persons, respectively.

“It is now incumbent on the US Centers for Disease Control and Prevention to determine who most benefits from booster dosing,” writes the author of an accompanying editorial.

Several study authors disclosed financial ties to the pharmaceutical industry, including Pfizer.

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