Clinical reactivity and immunogenicity of hemagglutinin influenza vaccine

Summary

The reactivity and immunogenicity of a polyvalent hemagglutinin influenza vaccine was studied in subjects aged 5–7 months. The vaccine was administered in three doses either subcutaneously (0.5 ml per dose) or intradermally (0.1 ml per dose) over a period of 6–7 months. Clinical reactions, both local and febrile, even after administering two or three doses, were quite mild. After two 0.5 ml doses of vaccine administered subcutaneously, most subjects possessed hemagglutination-inhibition (HI) antibodies to all the six vaccine viruses. In most subjects the antibodies dropped to und etectable levels in the course of four to five months. A booster effect was observed after the third vaccine dose. Intradermal administration of the vaccine (0.1 ml) was much less efficient. Even three doses of vaccine did not induce antibody development in most subjects. The antibody response in the complement-fixation (CF) test using strain-specific V antigens corresponded, in general, with the results of the HI test; however the CF antibodies to the A 2/Taiwan and B/Md viruses were found much less frequently than the corresponding HI antibody. Most of the infants vaccinated subcutaneously also developed antibodies reactive in the CF test with the soluble (S) antigens of influenza A and B. They were much less frequent in subjects immunized intradermally.