Preparation and characterization of live recombinant influenza vaccine.

Strain WRL 105 was prepared by recombination between the A/Finland/4/74 (H3N2) and attenuated A/Okuda/57 (H2N2) strains by a method previously described. A single intranasal dose of WRL 105 strain live attenuated influenza vaccine was administered to volunteers at three dose levels and homologous serum antibody titres and virus excretion were monitored. Doses greater than 10(6.3)EID50 gave 4-fold or greater increases in antibody titre in 80% of seronegative volunteers.