The effectiveness of the flu shot for the 2024-2025 and into 2025 season generally ranges around 40-60%. Recent interim estimates from the U.S and Germany report vaccine effectiveness (VE) approximately 31-56% overall, with higher effectiveness against flu-related hospitalization (up to 69%) and in children and adolescents (up to 78%). Protection is somewhat lower in adults under 60 and against certain influenza A strains like H3N2, which tends to show lower vaccine effectiveness compared to other strains. Despite variability year to year, vaccination significantly reduces the risk of severe illness, hospitalization, ICU admission, and flu-related death. Timing of vaccination also influences effectiveness, with September-October being an optimal window for most people to get durable protection through the flu season.

Key Points on Flu Shot Effectiveness This Year

• Typical flu shot effectiveness ranges from 40-60% but varies by age group and flu strain.

• Effectiveness in preventing hospitalization is often higher (up to nearly 70%) than in preventing milder illness.

• Children and adolescents tend to have better protection from the vaccine than adults, especially those under 60.

• Effectiveness against H3N2 influenza strain remains a challenge and tends to be lower.

• Flu vaccination reduces risks of severe outcomes including ICU admission and death.

• Optimal timing of vaccination for the season is generally September to October.

This evidence supports continuing to get the flu shot each year to reduce severe illness and complications even if the vaccine's protection level fluctuates.