HealthDay News — Receipt of a third dose of the BNT162b2 mRNA vaccine appears to be effective for reducing severe COVID-19 outcomes compared with receipt of 2 doses at least 5 months ago, according to a study published online October 29 in The Lancet.

Noam Barda, MD, from Clalit Health Services in Tel Aviv, Israel, and colleagues used data from Clalit Health Services, which provides mandatory health care coverage for more than half of the Israeli population to examine the effectiveness of a third dose of the BNT162b2 mRNA vaccine for preventing severe COVID-19 outcomes. Individuals receiving a third vaccine between July 30, 2021, and September 23, 2021, were matched to demographically and clinically similar controls who did not receive a third dose in a 1:1 ratio (728,321 in each group).

Participants were followed for a median of 13 days in both groups. The researchers found that compared with receipt of only two doses at least five months ago, at least seven days after receipt of the third dose, vaccine effectiveness for preventing severe outcomes was estimated to be 93% for admission to hospital (231 events for 2 doses vs 29 events for three doses), 92 percent for severe disease (157 vs 17 events), and 81% for COVID-19-related death (44 vs 7 events).

“One of the main drivers of vaccine hesitancy has been a lack of information regarding the effectiveness of the vaccine,” a coauthor said in a statement. “This careful epidemiological study provides reliable information on third-dose vaccine effectiveness, which we hope will be helpful to those who have not yet decided about vaccination with a third dose.”

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Several authors disclosed financial ties to biopharmaceutical companies, including Pfizer.

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