The effectiveness of a COVID-19 vaccine booster against hospitalization drops sharply within months, according to a new study.
Effectiveness after 14 months of a two-dose primary series of the Moderna or Pfizer vaccines was just 19 percent, according to the new paper. That protection jumped to 89 percent after a booster, but dropped to 66 percent between 4 and 6 months and to 31 percent after eight months.
The protection was the worst for young adults, declining to just 33 percent after four months, researchers found. The protection was more sustained for persons aged 65 or older but still declined under 50 percent after eight months.
The effectiveness estimates were against COVID-19-associated hospital admissions, or hospitalizations where the person who was admitted tested positive for COVID-19….