It is caused by a virus that spreads from infected persons to the nose or throat of others. Influenza can cause fever, sore throat, cough, chills, headache, or muscle aches. People of any age can get influenza. Most people are ill with influenza for only a few days, but some get much sicker and may need to be hospitalized. Influenza causes thousands of deaths each year, mostly among the elderly.
Influenza vaccine can prevent influenza.
The viruses that cause influenza change often. Because of this, influenza vaccine is updated each year by replacing at least one of the vaccine viruses with a newer one. Protection develops 2 weeks after that shot and may last up to a year. Residents of long term care facilities housing person with chronic medical conditions. Anyone whose immune system is weakened because of diseases that effect the immune system, treatment with drugs, and cancer treatment.