Vaccination policies in the military: an insight on influenza.

Influenza, despite its generally benign clinical course, is accompanied by absenteeism from work, acute suffering and even mortality, mainly in the elderly and in subjects who have high-risk medical conditions. Its prevention consists of strain specific vaccination, which must be repeated annually due to the high antigenic variability of the influenza virus. Influenza may represent an important obstacle to military readiness, particularly when considering its infectivity within closed communities.