The Effects of Birth Year, Age and Sex on Hemagglutination Inhibition Antibody Responses to Influenza Vaccination

The first exposure to influenza is thought to impact subsequent immune responses later in life. The consequences of this can be seen during influenza epidemics and pandemics with differences in morbidity and mortality for different birth cohorts. With the development of new universal vaccines there is need for better understanding of how vaccine responses are affected by early exposures to influenza viruses. In this analysis of hemagglutination inhibition (HI) antibody responses in two cohorts of military personnel we noticed differences related to birth year. These data suggest that HI antibody production, in response to influenza vaccination, is affected by influenza activity in the years following birth. The magnitude of this antibody response is associated with, among other factors, the influenza strain that circulated following birth.