MINNEAPOLIS (AP) — Flu season in Minnesota is off to an unusual start, with the B strain of influenza causing most of the lab-confirmed cases instead of the usual A strain.

The Star Tribune reports that the Minnesota Department of Health released data Thursday showing that B strains made up about 80% of the positive flu specimens obtained in clinics and hospitals that were tested in the first week of December.

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A strains appeared first in the state’s past 10 flu seasons and did most of the damage.

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B strains barely registered until February. The B strains have historically spread faster among children.

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