The flu is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. Every year in the United States, on average, 5% to 20% of the population gets the flu; more than 200,000 people are hospitalized from flu complications; and about 36,000 people die from the flu.
Symptoms of the flu include fever, runny or stuffy nose, headache, muscle aches, extreme tiredness, dry cough, and sore throat. Stomach symptoms such as vomiting and diarrhea can also occur but are more common in children than in adults.
Some people, such as older people, young children, and people with certain health conditions, are at high risk for serious flu complications. Complications of the flu can include pneumonia, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes. Children may get sinus problems and ear infections.
Flu viruses spread in droplets caused by coughing and sneezing. They usually spread from person to person, though sometimes people become infected by touching something with flu viruses on it and then touching their mouth or nose. Most healthy adults may be able to infect others beginning one day before symptoms develop and up to five days after becoming sick. That means that you can pass on the flu to someone else before you know you are sick as well as while you are sick.
The best way to prevent the flu is to get a flu vaccination each fall. October or November is the best time to get vaccinated. However, getting vaccinated in December or even later can still be beneficial. Flu season can begin as early as October and last as late as May.
There are two types of vaccines: the flu shot and the nasal spray vaccine. The flu shot is an inactivated vaccine, containing killed virus. It is given with a needle. The flu shot is approved for use in people older than six months, including healthy people and people with chronic medical conditions.
The nasal spray flu vaccine is made with live weakened flu viruses that do not cause the flu. This vaccine is approved for use in healthy people five years to forty-nine years of age who are not pregnant. About two weeks after vaccination, antibodies develop that protect against influenza virus infection. Flu vaccines will not protect against influenza-like illnesses caused by other viruses.
Certain people should get vaccinated each year. They are people who are either at high risk of having serious flu complications or people who live with or care for those at high risk for serious complications, including all health care workers. Other people who should get vaccinated each year are those who live in long-term care centers, adults and children with chronic heart and lung conditions, people with diabetes, anyone with HIV/AIDS, and women who will be pregnant during the flu season. If you are wondering if you should get a flu shot, talk with your doctor.