Epidemiologic Implications of the Distribution by Age of Antibody Response to Experimental Influenza Virus Vaccines

Abstract

A comparison of the frequency and magnitude of heterologous antibody increase to monovalent vaccines in three age groups demonstrates that people over 30 yeras of age have had maximal experience with swine-like strains of influenza virus, less with Type A strains and at least with A prime viruses. Children under 11 years of age have experienced influenza A-prime almost exclusively. The comparison also indictaes that the pattern of age specific attack rate of influenza A-prime infection is similar to the pattern of age specific attack rate determined by house-to-house surveys during epidemic prevalences of influenza A and swine-like strains. An estimation, allowed by the data presented, of the frequency of infection with influenza viruses during three major periods of prevalence indicates that the amount experienced by the polulation in recent years is similar to the amount experienced in previous periods. This finding, in light of the smaller incidence of disease observed in recent years, forces the interference that influenza A-prime viruses are of lesser virulence that Type A or like strains.