A fourth dose of the COVID-19 vaccine from Pfizer Inc (NYSE:PFE) and BioNTech SE (NASDAQ:BNTX) provided significant protection against severe disease, hospitalization, and death for at least a month in older individuals. The study was conducted in Israel, when the Omicron variant was dominant.
The estimated effectiveness of the fourth dose during days 7 to 30 after administration was 45% against infection, 55% for symptomatic disease, 68% for hospitalization, 62% for severe illness, and 74% for death compared with a third dose given at least fourth months earlier.
