A/USSR and B/Hong Kong vaccine. Field experiences during an A/Brazil and an influenza B epidemic

H. M. Foy, I. Allan, J. M. Blumhagen, M. K. Cooney, C. Hall and J. P. Fox

Young adults vaccinated in late spring of 1978 with one dose of vaccine containing either 7 microgram or 20 microgram of A/USSR (H1N1) hemagglutinin, followed by a dose of trivalent (A/USSR, A/Texas, B/Hong Kong) vaccine, were observed through an epidemic of A/Brazil influenza in the winter of 1978-1979, and of influenza B in 1979-1980. Influenza infection was diagnosed by virus isolation or serological titer rises between the spring seasons of 1978, 1979, and 1980. During the A/Brazil epidemic, rates of reported influenza-like illness and serologically confirmed H1N1 influenza infections were similar for all vaccine groups and two control groups. Naturally acquired antibody, but not vaccine-induced hemagglutination-inhibiting antibodies (HAI), appeared protective. During the influenza B epidemic, a lower rate of serologically confirmed infections was observed in the 1978 vaccine cohort than in one control group.