NEW YORK (December 3, 2012)—The flu season is off to its earliest start in nearly 10 years and it could be a bad one, officials with the U.S. Centers for Disease Control and Prevention said Monday.

The primary strain circulating is one that tends to cause more severe illness, especially in the elderly, but CDC officials said the nation seems to be fairly well prepared.

More than a third of Americans have been vaccinated, and the vaccine is well matched to the strains of flu so far.

Officials said Monday that suspected flu cases have jumped in five southern states including Alabama, Louisiana, Mississippi, Tennessee and Texas.

An uptick in flu reports like this usually doesn't occur until after Christmas.

The last time a typical flu season started this early was the winter of 2003-04.