Influenza (also known as flu) is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. Flu is different from a cold, and usually comes on suddenly. Each year flu viruses cause millions of illnesses, hundreds of thousands of hospital stays and thousands or tens of thousands of deaths in the United States.
Flu can be very dangerous for children. CDC estimates that since 2010, between 7,000 and 26,000 children younger than 5 years have been hospitalized each year in the United States because of influenza. The flu vaccine is safe and helps protect children from flu.
While flu illness can vary from mild to severe, children often need medical care because of flu. Children younger than 5 years and children of any age with certain long-term health problems are at high risk of flu complications like pneumonia, bronchitis, sinus and ear infections. Some health problems that are known to make children more vulnerable to flu include asthma, diabetes and disorders of the brain or nervous system.
Flu viruses are thought to spread mainly by droplets made when someone with flu coughs, sneezes or talks. These droplets can land in the mouths or noses of people who are nearby. A person also can get flu by touching something that has flu virus on it and then touching their mouth, eyes, or nose.
Flu symptoms can include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills, feeling tired and sometimes vomiting and diarrhea (more common in children than adults). Some people with the flu will not have a fever.