Optimizing Protection Against Influenza in Children Eligible for the Vaccine for Children Program

Abstract

Children eligible for the Vaccines for Children (VFC) program are immunized against influenza at lower rates and less likely to receive their second recommended dose. Live, attenuated influenza vaccine (LAIV) has higher vaccine efficacies (VEs) than trivalent, inactivated influenza vaccine (TIV). Increased use of LAIV could provide better protection against influenza for this vulnerable population. Published VE estimates and vaccine utilization data from a nationwide study of randomly selected pediatric practices were used to model percentages of VFC children that would be immune following immunization. A total of 22,329 influenza vaccine doses were administered to 20,626 VFC-eligible children aged 24 months to 17 years in the study population. Among children recommended to receive 2 doses, only 1234 of 3018 (41%) aged 24 to 59 months and 469 of 1908 (25%) aged 5 to 8 years received their second dose. Of the vaccinated VFC population, 73% to 83% would be immune using LAIV compared with 53% to 68% with TIV. Differences in aggregate immunity were greatest among 24- to 59-month olds with 71% to 78% of LAIV immunized children immune compared with 48% to 60% with TIV. In this model, 29% to 47% more children aged 24 to 59 months would be immune prior to peak influenza season when vaccinated with LAIV. Because VE is higher and most VFC children fail to receive their second recommended dose, population protection is substantially higher with LAIV. Although LAIV cannot be given to all children, LAIV should be used preferentially for the VFC population, particularly for children aged 24 to 59 months and those needing 2 doses.