Flu vaccines are safe and effective, and vaccination is the primary means of preventing influenza and reducing the damage from flu epidemics.

Seasonal flu epidemics can lead to significant levels of morbidity, hospitalization, and mortality during the fall and winter months.

Although influenza virus infection is usually mild and uncomplicated, it can also lead to severe illness, especially in older adults, residents of long-term care facilities, other vulnerable groups, pregnant women, people with medical co-morbidities, and young children. The clinical manifestations of influenza range from fever, cough, body aches, and headache to severe primary viral pneumonia, which may be complicated by secondary bacterial infection and exacerbation of existing chronic conditions. Influenza vaccination is the safest and most effective measure to prevent infection and severe outcomes caused by influenza viruses.