A flu epidemic has spread across the US, with 15 child deaths reported in nine states so far, according to federal health officials.
It’s not possible to predict how bad this flu season will be like. Flu seasons are unpredictable in a number of ways. While flu spreads every year, the timing, severity, and length of the season usually varies from one season to another.
Flu viruses are constantly changing so it's not unusual for new flu viruses to appear each year. For more information about how flu viruses change, visit How the Flu Virus Can Change.
The timing of flu is very unpredictable and can vary from season to season. Flu activity most commonly peaks in the U.S. between December and February. However, seasonal flu activity continues to infect people as late as May.