Adults who received a booster dose of Pfizer's COVID-19 vaccine are 11 times less likely to be infected after 12 days, according to a preprint study released Aug. 27 by Israeli researchers.
The real world study included more than 1 million people ages 60 or older who received a third dose of Pfizer's COVID-19 at least five months after their second dose. The study took place in Israel, which approved COVID-19 boosters this summer.
The study also found that booster doses lowered the risk of severe disease more than 10-fold. The researchers noted that this figure, as well as the 11-fold decrease in infection risk, is an estimate.
The research is preliminary, and its findings still need to be confirmed with further investigation. One of the study's limitations is that the people who received Israel's first booster shots may have been more risk-averse than the general population.
U.S. officials have been examining the data presented in the study to help inform decisions on Americans' booster timeline, according to The Wall Street Journal.