Boosted People More Likely Than Unvaccinated to Be Infected: Study

A health worker fills a syringe with a Pfizer-BioNTech COVID-19 vaccine in a file image. Emmi Korhonen/Lehtikuva/AFP via Getty Images

People who received a new COVID-19 vaccine booster were more likely to contract COVID-19 than people who received no COVID-19 vaccine doses, according to a new study of prisons in California.

Researchers analyzed data from 33 state prisons from January to July 2023 to try to assess the effectiveness of the bivalent shots, which were introduced in the fall of 2022.