Bivalent Covid Boosters Give Some Protection in CDC Study, But Not Much

Covid-19 boosters from Moderna Inc. and the partnership of Pfizer Inc. and BioNTech SE that fight the latest omicron variants provide only modest short-term protection against mild infections, and experts say it’s still unclear whether the updated shots are any better than earlier versions at preventing hospitalization and severe illness. The bivalent boosters were just 43% effective at preventing mild illness compared to receiving no vaccine in adults 49 and under, according to a US Centers for Disease Control and Prevention study published Tuesday. In those aged 50 to 64 years, comparative protection against symptomatic Covid was 28%, while the booster was just 22% protective in adults 65 and older, the study showed.