Antibody responses to influenza vaccines containing A/USSR/90/77

Studies were undertaken in adult groups aged 17-24 years, 25-64 years and 66-100 years to determine the haemagglutination-inhibiting antibody responses to sub-unit influenza containing A/USSR/90/77 (H1N1). Antibody responses to A/USSR/90/77 were low in all groups. The young adult group (17-24 years) produced a primary response to A/USSR/90/77 and showed a significant response to a second dose of vaccine, whereas their responses to the A/Texas/1/77 (H3N2) and B/Hong Kong/8/73 components were of the anamnestic type and showed no significant increase to a second dose. The adult (25-64 years) and aged (66-100 years) groups responded anamnestically to all three vaccine components. There was no impairment of the antibody response in the aged group in comparison with the response in the adult group. A comparative assay in microtitre trays and WHO plates showed two- to four-fold differences in antibody titre to A/USSR/90/77 in these systems.