Common symptoms include fever , chills, headache , sore throat , c ough, muscular aches and sometimes gastrointestinal disturbances. In healthy adults, the flu will usually run its course and subside within a week or two.
Influenza occurs in seasonal epidemics.
In the United States, the flu season is during the winter months and the highly contagious virus spreads rapidly through communities. The strains of viruses that cause the flu change from year to year and so do the symptoms and severity of the illness. Vaccinations are available each year to protect against the current strain of influenza. Given in the fall, vaccinations become effective within two weeks to protect against the flu. Flu vaccinations are recommended for anyone who has a chronic or debilitating disease, people over 65 years of age, health care workers, travelers to countries where the flu is prevalent and anyone who is at high risk of exposure to the virus.