Tweet Chat Wrap Up: What You Need to Know About the Flu The CDC says flu season is underway. Flu season is in full swing, with the Centers for Disease Control and Prevention reporting 20 states with high disease activity this year. With so much sniffling, coughing and sneezing making the rounds, ABC News Health held a tweet chat on Tuesday to help you protect you and your family from this seasonal illness. During the hour-long chat, there were more than 1,700 tweets from top organizations, hospitals and flu sufferers from all over the country. Our statistics show that the chat had nearly 40 million social media "exposures" - that's 22 million fewer people compared to the numbers exposed to the flu each year, according to the Robert Wood Johnson Foundation. In case you missed the chat, it's not too late to learn everything you need to know about the flu. Here is a sampling of the best tweets from the hour. What's the strain of flu this year? Who is at greatest risk for getting the flu? Is there a difference between the cold and the flu? Our experts say vaccination isn't perfect but it's the best way to prevent the flu. Some other great tips for flu prevention.