Trivalent inactivated influenza vaccine (TIV) immunogenicity in children 6 through 23 months of age: do children of all ages respond equally?

We assessed the effect of age on immunogenicity to trivalent inactivated influenza vaccine (TIV) by comparing the immune responses to influenza vaccine antigens among three age cohorts of vaccine-naïve children aged 6-11 months, 12-17 months, and 18-23 months. In children 6-23 months of age, antibody responses to TIV appear to increase with increasing age. Despite this finding, TIV was immunogenic even in the youngest age group evaluated, further establishing its value as a tool to protect young children from influenza. The role of age should be considered when assessing improved vaccines to enhance TIV immunogenicity and effectiveness in younger children.