Booster shots of the Pfizer-BioNTech and Moderna COVID-19 mRNA vaccines protected against hospitalization during this winter’s Omicron surge, but lose a substantial amount of effectiveness after about four months, according to a new study published Friday (February 11) by the Centers for Disease Control and Prevention.
Researchers found that mRNA vaccines remained highly effective against both moderate and severe cases of COVID-19 for about two months after a third dose, but the boosters’ effectiveness dropped substantially by four months. The study suggests that those at high risk of severe disease from SARS-CoV-2 infection may need additional booster shots.
In the study, researchers measured how effective COVID-19 mRNA vaccines—either Pfizer-BioNTech or Moderna—were at preventing both hospitalization and visits to emergency departments or urgent care facilities. Using data from 10 US states gathered between August 26, 2021 and January 22, 2022, the researchers analyzed 241,204 visits to emergency departments and urgent care ...
