Influenza Vaccine Effectiveness Lower in Recent Months, Preliminary Data Show

Officials presented the estimates during a meeting on March 12.

An influenza vaccine in a doctor's office in Coral Gables, Fla., on Sept. 15, 2025. Joe Raedle/Getty Images

The effectiveness of vaccines against influenza dropped during the 2025–26 virus season, officials said on March 12, about two months after the Centers for Disease Control and Prevention stopped recommending flu vaccination for all children.

Vaccine effectiveness for late 2025 and early 2026 against outpatient visits and hospitalization was pegged at 14 percent to 48 percent among children, Dr. Lisa Grohskopf with the CDC’s Influenza Division told a meeting hosted by the Food and Drug Administration.