ARTIFICIALLY INDUCED ASIAN INFLUENZA IN VACCINATED AND UNVACCINATED VOLUNTEERS

Abstract

Fever, chills, and other symptoms characteristic of influenza appeared in 18 out of 23 (78%) unvaccinated volunteers about 38 hours after the nasopharynx was sprayed with nasopharyngeal secretions containing living virus from three influenza patients. The virus was influenza A/Valley Forge/57, which was antigenically similar to the Far East strain. When the same material was administered to 32 volunteers who had been vaccinated against influenza A/Japan/305/ 57, the cases of febrile illness numbered 14 (44%). The vaccination and the challenge inoculation both induced a hemagglutination inhibition antibody response. Influenza virus was recovered from 14 (41%) of ill volunteers. The vaccination therefore gave significant though incomplete protection against Asian influenza.