Influenza vaccine effectiveness by age for Influenza A/B viruses between 2011-2020

Understanding whether influenza vaccine effectiveness (VE) varies by age is crucial to determine which populations need refinements in vaccination strategy or additional measures to reduce influenza rates, hospitalizations, and deaths. Our objective was to analyze the mean VE for different strains of influenza across five age groups: 6 months–8 years, 9–17 years, 18–49 years, 50–64 years, and 65+ years old. We used VE data for Influenza A, H3N2, and H1N1 strains, and Influenza B vaccines from the Centers for Disease Control and Prevention (CDC), collected between 2011–2020. We compared VE rates across different years, strains, and age groups. Overall, VE varied significantly by year, strain, and age group (p < 0.05, one-way ANOVA). The youngest age group (6 months–8 years) had a significantly higher VE than both the 18–49 years old and 65 years old or greater age groups (p<0.05, one-way ANOVA). Future vaccine development should be tailored to these two distinct populations to ensure adequate protection against influenza.