Abstract
This study was conducted to test the limits of the doctrine of 'original antigenic sin' in influenza A. The design included use of zonal purified 1000 CCA (chick cell agglutinating) units monovalent vaccines consisting of H0N1, H1N1, H2N2 and H3N2. Age cohorts with different primary influenza A infections were established for the 687 volunteers. The vaccines administered to each age cohort were selected to test the responsiveness of original antigenic sin antibody to homologous and heterologous challenge. Anamnestic responses were demonstrated with Hsw1n1,H0N1, and H1N1 and with H2N2 and H3N2 but not between the groups. The synthesis of these findings is that there are 2 original antigenic sins - 2 families of influenza A viruses.