LOS ANGELES (CBSLA) — Public health officials are warning of a flu strain that is dominating this season.

According to Mission Hospital Chief of Staff Dr. Jim Keany, the A strain of Influenza is usually seen early in the season but there is currently a spike in the number of people infected with the B strain.

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The A strain can mutate and poses the biggest risk for widespread infection but the B strain, that usually shows up later in the spring, is seen as more dangerous to young children.

The CDC reported that in the first three weeks of December, three small children died from flu-related illnesses all linked to the B strain.

“Right now, we’re seeing a B strain surge,” said Keany.  “The B strain is included every year. There are two predominant types of B strain and now the new flu shots are what we call quadrivalent shots, so it has two of the A’s and two of the B’s.”

Experts are unsure why the B strain is making an early appearance this season, but they say overall, the symptoms between A and B aren’t very different.

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“What we’ve noticed is people coming in with a lot more sore throat this year, a lot more vomiting on occasion, which usually isn’t part of the flu, and then not always a high fever,” said Keany. “It is also treated by Tamiflu just like the A strain so it’s a really good idea to see a doctor in the first 72 hours.”

Dr. Keany advises people to protect themselves from both strains by getting a flu shot.

Studio City resident Laura Hollis said she gets the flu shot every year saying, “I do just as a precaution. Some years it’s helped, some years it hasn’t. Last year, it helped quite a bit.”

However, Sylmar resident Manny Hernandez said he doesn’t see a need for the shot saying, “People do tell me ‘Oh, you should go get the flu shot’ but I myself don’t really see a need for it.”

Across the country, the flu has caused at least 4.6 million flu illnesses, 39,000 hospitalizations and 2,100 deaths since the season began in September.

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Health official advise those in high-risk groups should get the flu shot. Those groups include young children, people 65-years-old and older, people with heart and respiratory illnesses, and pregnant women.