A clinical trial of WRL 105 strain live attenuated influenza vaccine comparing four methods of intranasal vaccination.

A single intranasal dose of 10(7.0)EID50 recombinant WRL 105 strain live attenuated influenza vaccine was administered intranasally to 193 volunteers either as nose drops or by one of three spray devices which produced sprays of differing physical characteristics. In volunteers with homologous hemagglutinating inhibiting antibody titres of less than or equal to 20 before vaccination, seroconversion rates varied widely from 80% following the administration of drops to 71%, 57% and 28% with each of the spray devices. In the week following vaccination 16 (22%) of 74 volunteers who were found to show a fourfold or greater antibody response took analgesics to control symptoms in comparison with 4 (7%) of 58 volunteers who exhibited no serological response to vaccination (p less than 0.05). However, neither of the occurrence of upper respiratory nor systemic symptoms were significantly different in these two groups and the level of attenuation of the recombinant WRL 105 strain appears to be acceptable for future use.