What causes the flu in a child?

The flu is caused by flu viruses. Flu viruses are divided into 3 types:

• Influenza types A and B. These 2 types of viruses cause widespread illness (epidemics) almost every winter. They often lead to more people needing to go to the hospital, and more people dying from the flu. Public health officials focus on stopping the spread of types A and B. One of the reasons the flu remains a problem is because the viruses change (mutate) often. This means that people are exposed to new types of the viruses each year.
• Influenza type C. This type of virus causes a very mild respiratory illness or no symptoms at all. It does not cause epidemics. It does not have the severe public health impact that influenza types A and B do.

A flu virus is often passed from child to child through sneezing or coughing. The virus can also live for a short time on surfaces. This includes doorknobs, toys, pens or pencils, keyboards, phones and tablets, and countertops. It can also be passed through shared eating utensils and drinking. Your child can get a flu virus by touching something that was touched by an infected with person, and then touching his or her mouth, nose, or eyes.

People are most contagious with the flu 24 hours before symptoms start, continuing while symptoms are most active. The risk of infecting others usually stops around day 7 of the illness. Because the flu can be spread before symptoms start, it’s easy to pick up a flu virus. This is true especially with children, who often touch many surfaces and then their mouth, nose, or eyes.