Abstract
Field trials of live influenza vaccine were carried out in Osaka in November 1964. In February in 1965, outbreaks of influenza A2 epidemic were observed. Morbidity rate of 3, 464 vaccinated persons was 13.2% and 1, 429 unvaccinated persons was 26.6% and effectiveness coefficiency was 2.0. Epidemic was remarkably lower in the schools vaccinated by live influenza vaccine than in the neighbouring schools vaccinated by inactivated vaccine. Period needed to stay away from school or work for infected persons was 2.3 days in the vaccinated persons and 3.0 days in the unvaccinated persons. Mean maximal fever was 38.4°C and 38.6°C respectively.
