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. The H1N1 flu strain is reported to be the most predominant of the three strains circulating.
So far, public health officials are not reporting any notable activity in Illinois.
In Britain, health officials say flu has now killed 27 people and transmission of the virus is picking up across Europe.
Health officials say an estimated 23,600 flu-related deaths occur each year.
The Associated Press contributed to this report.