UNDATED (CNN) -- The Centers for Disease Control is warning the flu season appears to be bad this year, spreading faster and earlier than usual.
The CDC says the South and Southeast section of the country is getting hit hard. Even people who received the flu shot can still get sick.
"Number one it does take some time for the vaccine to take effect and if you are exposed to influenza a very short time after getting the vaccine you can still get infected," said Dr. Michael Jhung, Medical Officer in the Influenza Division. "Number two there's a lot of influenza viruses out there. The influenza vaccine will protect against three of those viruses."
There is one theory that the outbreak may be due, in part, to the possibility that the flu vaccine does not include the strain that is currently spreading across the country. But the CDC disagrees, saying the influenza virus people are being infected with appears to be covered by this year's vaccine.