Reactogenicity and immunogenicity of three inactivated influenza virus vaccines in children

Abstract

The reactogenicity and immunogenicity of an aqueous inactivated whole virus vaccine, splitvirus vaccine and a subunit vaccine was studied in young children. In volunteers aged 9–12 years inoculated with two doses of vaccine given 1 month apart, the number of reactions seen following both immunization with either whole virus or subunit virus vaccine was small; the reactions were all mild in nature; and both vaccines gave comparable results. Two doses of vaccine induced relatively high tires of serum HI antibody against A/Texas/77 virus, but poorer responses against influenza A (H1N1) virus and B/Hong Kong/73 virus; the serum HI antibody responses were similar for the two vaccines. The incidence of local reactions in volunteers aged 5–9 years given two doses of whole virus, subunit or split-virus vaccines was also low, and mild in nature: all three vaccines gave similar results; however, systemic reactions occurred more frequently in volunteers given whole virus vaccine than in those inoculated with subunit or split-virus vaccines, but the differences were not statistically significant. The serum HI antibody responses were similar for the three influenza vaccine forms: the response to the A/Texas/77 virus haemagglutinin was relatively satisfactory but poor antibody responses were found for the influenza A (H1N1) and B/Hong Kong/73 haemagglutinins. In addition, the response of volunteers aged 5–9 years to influenza virus A (H1N1) haemagglutinin was significantly less than for volunteers aged 9–12 years.