Was the fourth dose of Pfizer's COVID-19 vaccine effective? -study - The Jerusalem Post

Researchers from the epidemiology and preventive department at Tel Aviv University’s Sackler Faculty of Medicine, Soroka University Medical Center in Beersheba, Ben-Gurion University of the Negev’s Faculty of Health Sciences and the Health Ministry’s geriatric department and Senior Shield Project studied the medical records of 24,088 elderly recipients living in long-term-care geriatric facilities who received a fourth dose, and those of 19,687 who received only three doses four months previously or earlier.

“Elderly residents of long-term-care facilities are at high risk for severe and fatal COVID-19, with reduced immunity...

“Elderly residents of long-term-care facilities are at high risk for severe and fatal COVID-19, with reduced immunity … and rapid decline in the immune response after two vaccine doses.”.

The vaccination campaign for the third dose in geriatric patients began in August 2021 and was associated with high vaccine uptake and rapid declines in the incidence of SARS-CoV-2 infection and COVID-19 hospitalizations.

Indeed, among the general Israeli population 60 years or older, wrote the team, the protection granted by the fourth dose was estimated at 45% to 50% against SARS-CoV-2 infection.