The effect of influenza vaccination on the circulation of viruses in the respiratory tract of apparently healthy schoolchildren aged 7 to 14 years.

Virus isolation attempts were made with 500 nasopharyngeal secretion samples from apparently healthy schoolchildren aged 7-14 years, vaccinated by nasal route with an inactivated influenza vaccine and with 500 samples from unvaccinated schoolchildren of the same age. The number of virus isolates obtained was much smaller in the former than in the latter group (13 as against 50 virus isolates). The role of influenza vaccination in the protection of schoolchildren against respiratory tract infections is discussed.