Flu is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs. It can cause mild to severe illness, and at times can lead to death.

The best way to prevent flu is by getting a flu vaccine each year.  Influenza can cause mild to severe illness, and at times can lead to death. Flu is different from a cold. Flu usually comes on suddenly. People who have the flu often feel some or all of these symptoms: Cough, fever, sore throat, runny or stuffy nose, headaches, fatigues, and some people may have vomiting and diarrhea.

Most experts believe that flu viruses spread mainly by tiny droplets made when people with flu cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby. Less often, a person might get the flu by touching a surface or object that has flu virus on it and then touching their own mouth, nose or possibly their eyes.  The same CID study found that children are most likely to get sick from the flu and that people 65 and older are least likely to get sick from influenza.

Median incidence values (or attack rate) by age group were 9.3% for children 0-17 years, 8.8% for adults 18-64 years, and 3.9% for adults 65 years and older. This means that children younger than 18 are more than twice as likely to develop a symptomatic flu infection than adults 65 and older.

For most healthy people, the flu is an uncomfortable but short-term illness that resolves itself as the immune system fights it off. Symptoms usually appear from one to for days after exposure to the virus, and they last five to seven days. If you’re able to limit contact with people during the flu season, you can reduce your risk of getting an infection.