Flu Vaccine Effectiveness Lower for 2025-2026 Season, CDC Reports

HealthDay News — Interim data suggests the influenza vaccine may be less effective during the 2025-2026 season compared to recent years, but still offers valuable protection against the flu, according to research published March 12, 2026, by the U.S. Centers for Disease Control and Prevention (CDC).

Interim Vaccine Effectiveness Estimates

Researchers, led by Patrick Maloney, Ph.D., from the CDC in Atlanta, calculated interim vaccine effectiveness (VE) estimates based on data from three U.S. Respiratory virus VE networks during the 2025-2026 influenza season. The analysis focused on acute respiratory illness-associated outpatient visits and hospitalizations.

Effectiveness in Children and Adolescents

Among children and adolescents under 18 years of age, the vaccine demonstrated 38% to 41% effectiveness against influenza-related outpatient visits. Protection against influenza-associated hospitalization in this age group was slightly higher, at 41%.

Effectiveness in Adults

For adults aged 18 years and older, VE ranged from 22% to 34% against influenza-related outpatient visits and 30% against influenza-associated hospitalization.

Strain-Specific Effectiveness

VE against influenza A varied depending on the setting. Among children and adolescents, it ranged from 37% (outpatient visits) to 42% (hospitalization). For adults, VE against influenza A ranged from 30% (hospitalization) to 34% (outpatient visits). Specifically, VE against influenza A(H3N2)-associated outpatient visits and hospitalization was 35% and 38%, respectively, in children and adolescents. Vaccine effectiveness against influenza B outpatient visits was notably higher, ranging from 45% to 71% among children and adolescents and reaching 63% among adults.

Importance of Vaccination Remains

The authors emphasize that even with reduced overall VE, influenza vaccination remains a crucial public health measure. “Even in seasons when overall VE is reduced, influenza vaccination has prevented thousands of hospitalizations and deaths,” they wrote in the report published by the CDC.

Key Takeaways

• Interim data indicates the 2025-2026 influenza vaccine is less effective than in recent seasons.
• Vaccine effectiveness varies by age group and influenza strain.
• Despite lower effectiveness, vaccination still provides significant protection against severe illness, hospitalization, and death.
• Annual influenza vaccination is recommended for all individuals aged 6 months and older.

The CDC continues to recommend influenza vaccination, and U.S. Influenza vaccines remain readily available for individuals aged 6 months and older. Further details can be found on PubMed.