A fast-spreading mutation is making this flu season more dangerous—especially for children. Here’s what to know and why getting vaccinated still matters.

Officials at the California Department of Public Health confirmed on Tuesday that a mutated influenza strain dubbed the “super flu” is spreading in California. 

The news came as the CDPH confirmed a second pediatric death related to the flu since the start of the respiratory virus season. The “super flu” strain is a mutated type of seasonal influenza A called H3N2 subclade K and has spread globally. 

Dr. Monica Gandhi, an infectious disease expert at UC San Francisco, said people infected with the mutated strain will likely get common flu symptoms, such as body aches, fever, cough and headache. 

“I think this particular strain makes people feel pretty horrible,” Gandhi told SFGATE. “And the reason that subclade K is important is it may not be covered by the current flu vaccine.” 

Flu activity in the state has come down slightly from a season high at the end of December, with about 15% of flu tests coming back positive in the state as of Jan. 3. That’s down from the 17% rate seen through Dec. 27. 

“It may start rising in California now, because people were sick when they went places … and there needs to be an incubation period,” she said. 

The best way to avoid the flu is to get the flu shot, which can provide important protection. Even when the vaccine isn’t a perfect match for the most prevalent strain, such as with the “super flu,” it can still drastically reduce the risk of developing dangerous symptoms. 

“Current seasonal flu vaccines remain effective at reducing severe illness and hospitalization, including the currently circulating viruses,” Dr. Erica Pan, CDPH director and state public health officer, said in a statement. “It is important for families to know that flu vaccines, tests, and treatments remain widely available for all Californians and that it is not too late to get a flu vaccine.” 

If you found this Health Matters update helpful, feel free to share it with someone you care about. It might be exactly what they need today.