Effectiveness of seasonal influenza vaccine in elementary and middle schools: a 10-year follow-up investigation.

Background: Influenza spreads from schools to the rest of society. Thus, we conducted questionnaire surveys of influenza vaccination in elementary and middle schools in a district for 10 years to determine immunization rates and infection conditions among students who were potential sources of infection at home.

Methods: The questionnaire-based survey on influenza vaccine administration, influenza infection, and influenza types contracted, as well as influenza immunization history, was conducted in 10 seasons over a period of 10 years.