Preliminary results of oral influenza vaccination with live attenuated viruses.

151 subjects, vaccinated by oral route with live influenza viruses attenuated in the USSR (bivalent A/England/42/72-B/Hong Kong/5/72 vaccine) and 66 non-vaccinated cohabitants have been studied. The vaccination did not cause any important side effect. The vaccine showed good immunizing activity: HI antibodies appeared in 91% of the subjects initially devoid of antibodies against A type and in 70% against B type. No viral diffusion occurred from the vaccinated to the cohabitants. During an A/Port Chalmers/1/73 epidemic the morbidity (3.3%) among the orally vaccinated patients turned out significantly lower than that among the non-vaccinated cohabitants (12.1%). The protection index was 72.6%.