PHILADELPHIA (CBS) -- This year's flu season is a record-breaker. It's now the middle of April, but Americans are still getting the flu.
An unexpected trend revealed by federal health officials Friday show a flu season that's the longest on record. After the holidays, it looked like it was going to be a short and mild season, but a surge of cases in March and April has changed things.
There's been a surprising second wave of the flu in the past several weeks, according to new figures released by the CDC, making this year's flu season one of the longest since 19997, when they started keeping records.
"This year was the longest flu season we've seen in the last ten years. Previously, the longest was 20 weeks and right now we're at 21," epidemiologist Lynnette Brammer of the CDC Influenza Division said.
One reason: two types of flu viruses surfaced at different times.
"The beginning of the season was H1N1 dominant, and then as that went down, H3N2 viruses went up," Brammer said. "We did have two different waves of influenza this year."
So far this season, up to 41.3 million people showed flu symptoms. Up to 19.4 million visited the doctor and as many as 610,000 were hospitalized.
While flu cases are declining now, doctors say the virus can still spread, even in the warmer weather.
"Given the way the flu season is going, if you have flu-like symptoms, there's a good chance you do have flu," Brammer said.
The CDC estimates as many as 57,000 people died from the flu this season, including 91 children.
With the flu still circulating, health officials say people should be cautious this holiday weekend. And while this has been the longest flu season, it's not nearly as bad as last winter, which was the deadliest in the last four decades.
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