Intranasal immunization with inactivated influenza virus vaccine in a boys' boarding school.

An influenza B epidemic which occurred in a boys' boarding school during the early part of 1974 is described; 41 per cent of the boys, 30 per cent of the masters and 38 per cent of the house masters developed influenza. The incidence of influenza was similar in all blocks in the school but variable in the boys' houses. The four-day half-term holiday which took place in the middle of the epidemic was of undoubted value in curtailing the spread of infection. Intranasal vaccination with a vaccine which did not contain specific protection against the subsequent epidemic was of slight benefit.