by Brooke Rogers | CBS 11

DALLAS (CBSDFW.COM) – It’s been an unusual flu season, one that started early and with a dominant strain that’s hitting children especially hard.

Positive flu cases started trickling in last September and the results surprised many doctors: the less common B strain outnumbered flu A.

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“Usually A is dominant, but this time we are seeing a flu B dominance,” said Dr. Glenn Hardesty, an ER Physician with Texas Health Resources. “Why that is, we’re uncertain. It could be related to the strain or some genetic mutation of the virus.”

Doctors say the flu vaccine isn’t as effective for flu B as flu A. And because children have been less exposed to the B strain, it can be more dangerous for them.

“Even though you’ve been vaccinated for many years potentially, you don’t have a ton of antibodies to flu B from prior exposures and from prior vaccinations,” said pediatrician Dr. Julie Linderman,

Dr. Linderman said her flu B patients this season have had more severe symptoms.

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“The majority of my patients have been presenting with fever, typically high fever, 103, 102, and muscle aches, headaches, fatigue.”

Though she says the symptoms are milder in those who had a flu shot. Dr. Glenn Hardesty said he suspects flu B will start to taper off, but what that will mean for the rest of the season is hard to predict.

“The hope is that we’ve seen our peak and will see a decline, but we might see another round of flu activity, because the first round was so early,” he said.

The B strain is actually less severe on the elderly than on children.

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Because of that, the CDC predicts the overall number of hospitalizations and deaths will be lower this year.