The latest map from the CDC shows Pennsylvania and Delaware have "widespread" flu activity.
That's the highest level.
Pennsylvania already has 1,280 lab-confirmed cases of flu, 990 of them are the more aggressive A-strain. About 250 of the confirmed flu cases thus far are in the Philadelphia area.
New Jersey is still a few steps behind with "local" activity.
Several states in the Midwest are reporting very high flu activity.
Some schools in Ohio and Illinois are doing extra cleaning after a significant percent of their students were out sick.
Two weeks ago, the Centers for Disease Control and Protection said the vaccine was only 50% effective against the H3N2 strain, the dominant one this flu season.
But Dr. Richard besser, ABC's Chief Medical Editor and a former director of the CDC, says the vaccine only covers about a third of the strains circulating.
So, it will be more important than ever to take your own preventative measures.
Stay home if you are sick, wash your hands often, and clean doorknobs, keyboards and other common areas.
This is especially important around the holidays, when we typically see a spike in the number of cases because more people are spending time indoors together.
There is also a new health app that can help you track if the flu or other illnesses are in your area.
It's called "Flu Near You."
You can report your symptoms such as fever, cough and sore throat.
And you can check out the map to see if people near you are also reporting symptoms.
For more information, visit Flunearyou.org
Keep tabs on the flu's progress:
Keeping track of rising flu activity in your area
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