A third shot of the Pfizer coronavirus vaccine reduces the chances of hospitalization by 93%, serious illness by 92% and mortality by 81%, according to an Israeli-American study published Friday night in the Lancet.
The study, which compared nearly 730,000 individuals who received the third shot against the same number who were vaccinated with two shots five months or more prior and did not receive the booster, was carried out by researchers from Clalit Health Services and Harvard University.
The observational study was done during the peak of the Delta wave – July 30 to September 23, 2021. It is the first study to be peer-reviewed that evaluates the effectiveness of a third dose of the Pfizer vaccine against serious outcomes while regulating for a variety of variables, including comorbidities and behavioral factors.
“These data provide immediate evidence for other countries now deliberating the need for a similar booster vaccination campaign” to Israel’s, said Ran Balicer, Clalit’s chief of innovation. “Every country will need to make its own decision based on its setting and the timeline of vaccinations that were provided over the last year.
“In Israel, it suggests that in view of its very early vaccination campaign and waning immunity, the decision for an early vaccination campaign was probably right and saved many lives,” he said.