Studies with a Cold-Recombinant A/Victoria/3/7S (H3N2) Virus. II. Evaluation in Adult Volunteers

Abstract
A cold-recombinant influenza A virus, CR 22, derived from A/Ann Arbor/6/60 (H2N2) cold-adapted virus and A/Victoria/3/75 (H3N2) wild-type virus, was tested in adult volunteers. CR 22 induced only low-grade clinical reactions in volunteers who had low titers of serum antibodies. Virus could be reisolated from about one-third of the volunteers-but only at low titers. No revertant viruses were found, and there was no evidence for transmission of virus to unvaccinated volunteers housed in close contact with the vaccinees. A high proportion of the volunteers seroconverted, and the mean titers of serum antibody after immunization suggest that a high degree of protection is induced by vaccination with live CR 22 virus.