Flu Shot Protection Lower for 2025-2026 Season, CDC Data Shows
Interim data from the Centers for Disease Control and Prevention (CDC) indicates that the influenza vaccine may be less effective during the 2025-2026 flu season compared to recent years. But, health officials emphasize that vaccination still offers significant protection against influenza, particularly against severe illness requiring hospitalization.
Interim Vaccine Effectiveness Estimates
Researchers, including Patrick Maloney, PhD, from the CDC in Atlanta, analyzed data from three U.S. Respiratory virus vaccine effectiveness (VE) networks. The findings, published in the March 12 issue of the CDC’s Morbidity and Mortality Weekly Report, provide early estimates of vaccine performance during the 2025-2026 influenza season.
Vaccine Effectiveness in Children and Adolescents
Among children and adolescents under 18 years of age, the vaccine demonstrated 38% to 41% effectiveness against influenza-associated outpatient visits. Protection against flu-related hospitalization in this age group was slightly higher, at 41%.
Vaccine Effectiveness in Adults
For adults aged 18 years and older, vaccine effectiveness ranged from 22% to 34% against influenza-associated outpatient visits. The vaccine offered 30% protection against hospitalization due to influenza in this age group.
Strain-Specific Effectiveness
The data likewise revealed varying levels of protection against different influenza strains:
- Influenza A: Vaccine effectiveness against influenza A ranged from 37% against outpatient visits to 42% against hospitalization among children and adolescents. For adults, VE ranged from 30% against hospitalization to 34% against outpatient visits.
- Influenza A(H3N2): Among children and adolescents, the vaccine was 35% effective against outpatient visits and 38% effective against hospitalization caused by the A(H3N2) strain.
- Influenza B: The vaccine showed stronger protection against influenza B, with effectiveness ranging from 45% to 71% among children and adolescents and 63% among adults against outpatient visits.
Importance of Vaccination Remains
Despite the lower overall effectiveness estimates, the CDC continues to recommend annual influenza vaccination for all individuals aged 6 months and older. Researchers emphasize that even in seasons with reduced vaccine effectiveness, vaccination plays a crucial role in preventing severe illness, hospitalizations, and deaths.
“Even in seasons when overall VE is reduced, influenza vaccination has prevented thousands of hospitalizations and deaths,” the authors wrote in the report.
Source: CDC Morbidity and Mortality Weekly Report
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