Observational study reveals cord blood antibodies delay influenza A infection in infants, indicating maternal vaccination protects newborns.
Key Points
To evaluate whether transplacentally transferred maternal antibodies protect infants under four months of age against influenza A virus infection.
Measured influenza A antibodies in cord blood collected between 1975 and 1978 using a microneutralization test and a radioimmunoprecipitation assay.
Analyzed cord sera and acute-phase sera from 26 infants younger than four months with culture-confirmed influenza A/Victoria (H3N2) infection.
Demonstrated a significant direct correlation between infant age at infection and the level of antibody in cord serum (P < 0.002).
Found no detectable antibodies to influenza A hemagglutinin by radioimmunoprecipitation assay in all 14 acute-phase serum samples collected early in infection.