The Centers for Disease Control and Prevention says five states had widespread reports of flu last week, up from zero two weeks earlier.
A CDC report released Thursday says four of the states were in the South Alabama, Mississippi, Georgia and Virginia. The other was New York.
The report also says that tests of about 120 virus samples show the circulating flu strains seem to be well-matched to this season's flu vaccine.
Health officials say an estimated 23,600 flu-related deaths occur each year.