Updated Covid vaccine has 54% effectiveness, new data suggest

New data released Thursday by the Centers for Disease Control and Prevention suggest that the most recent Covid-19 booster offers about 54% percent protection against infection with the virus.

A study published in the CDC’s online journal Morbidity and Mortality Weekly Report showed that the updated vaccine was essentially equally effective at protecting against the strain targeted by the vaccine — called XBB.1.5 — and the JN.1 subvariant, which emerged after the vaccine was made. JN.1 is currently the dominant virus circulating in the United States.

Ruth Link-Gelles, an author of the study, said it shows that the latest Covid shot offers significant protection to recipients.

“We know that Covid is continuing to cause thousands of hospitalizations and hundreds of deaths in this country each week,” Link-Gelles, the vaccine effectiveness program lead in the CDC’s National Center for Immunization and Respiratory Diseases, told STAT. “And 50% added protection against Covid-19 is really going to be a meaningful increase in protection, especially for those at highest risk.”

Arnold Monto, a veteran vaccine effectiveness researcher at the University of Michigan, said the findings are what are expected at this point for Covid vaccine boosters.