The consequence of influenza, commonly "the Flu", are often underestimated. Each year, influenza is responsible for many deaths in the United States and around the world. It must be stressed that other respiratory viruses cause similar symptoms at the beginning but normally consequences are less severe. Infection with influenza viruses can cause a whole spectrum of symptoms which can go from mild to severe. As a consequence people with underlying diseases and other risk factors can suffer from complications.

Influenza - 'flu' - is a highly infectious acute viral infection, which affects people of all ages, mainly during the winter months. It typically starts suddenly with fever, chills, headache, aching muscles, general prostration and usually a cough or other respiratory symptoms.

While most people recover without complications in 1-2 weeks, flu can cause serious illness and death, especially in the very young and the elderly. Flu epidemics result in widespread illness and disruption to health and other services.

A vaccine is produced every year based on the strains of virus expected to be circulating.

In the United States, the peak of flu season can occur anywhere from late December through March.  The health impact (infections and deaths) of a flu season varies from year to year.

Find out more about the flu by clicking on the topics below.