Clinical trials with a new influenza subunit vaccine in adults and children.

The reactogenicity and immunogenicity of a new influenza subunit vaccine containing essentially only hemagglutinin and neuraminidase has been studied in man. Studies in primed individuals demonstrated that the subunit vaccine induced antibody levels as high as those induced by a comparable whole virus vaccine, or a commercially available whole virus vaccine or by a split vaccine. The commercial whole virus vaccine caused systemic reactions, including fever and headache in 15% of volunteers. In contrast local and systemic reactions were significantly fewer after application of subunit vaccine. When unprimed individuals were vaccinated serological responses were, however, superior with whole virus vaccines. The subunit vaccine demonstrated good immunogenicity and a very low reactogenicity in children. Three months after vaccination, a number of the children were challenged intranasally with live attenuated influenza virus. All proved, as judged by virus isolation and antibody response to be resistant.