Flu levels are rising once again across the United States, with emergency department visits increasing among children over 5, according to data from the Centers for Disease Control and Prevention.

Flu cases and hospitalizations are surging, already breaking last season's records. Here's where activity is highest, what symptoms to watch for and how to protect yourself.

The flu epidemic continues to go down. The positivity rate and other benchmarks for the week ending on Jan. 24 have dropped compared with previous weeks, according to the latest data from the Centers for Disease Control and Prevention.

How long are you contagious with the flu? Experts say you can spread the virus for five to seven days after symptoms start, sometimes longer for children and adults.

Learn how Subclade K, a variant of the influenza A virus, is affecting immune responses and contributing to this year’s intense flu season.

Cases across the country had appeared to decline before new public health data showed upticks in infections.