[Influenza vaccination]

In view of its high morbidity and substantial mortality in risk subjects, influenza has been a focus of attention for decades. The special ability of influenza viruses to change their genetic codes and hence their antigenicity--thereby constantly cancelling out our specific acquired immunity--poses and annually recurring threat of local epidemics and pandemics potentially fatal for large sections of the population. Influenza vaccination can significantly lower morbidity and mortality. It involves few side effects, is efficacious and cost effective . It is one of the most efficient primary preventive measures in all of medicine. The present state of knowledge is reviewed.