STUDIES ON INACTIVATED INFLUENZA VACCINES .I. EFFECT OF DOSAGE ON ANTIBODY RESPONSE AND PROTECTION AGAINST HOMOTYPIC AND HETEROTYPIC INFLUENZA VIRUS CHALLENGE IN MICE

Kaye, H. S. (Respiratory Virology Unit, NCDC, Atlanta, Georgia 30333), W. R. Dowdle, and J. L McQueen, Studies on inactivated influenza vaccines. I. The effect of dosage on antibody response and protection against homotypic and heterotypic influenza virus challenge in mice. Amer. J. Epid., 1969, 90: 162-169.-An A2/Japan/305/57 monovalent influenza vaccine provided complete protection against challenge of mice with representative A2 viruses isolated over a seven-year span. The vaccine was less effective against the 1967 A2 strain. Protection against heterotypic strains was clearly related to vaccine dose. Vaccine potency values obtained varied widely depending on the test employed and the parameter of measurement used. However, tests based on the per cent of mice resisting challenge or on absence of significant antibody response after challenge seemed to best reflect antigenic differences and true protection. The results of this study suggest that with increased vaccine dosage good protection is afforded against heterotypic strains isolated over a long period of time; however, protection is reduced with continued antigenic drift. © 1969, by THE JOHNS HOPKINS UNIVERSITY.