Some people who claim to have what they believe is the flu or stomach flu may have something else instead.

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Norovirus is increasingly common and features some of the same symptoms as flu. But Dr. Christopher Belcher, a pediatric infectious disease specialist at Peyton Manning Children's Hospital, says norovirus has a shorter duration, usually a couple days, whereas flu symptoms can last a week or more.

Belcher says norovirus comes on quickly and has symptoms including vomiting, abdominal pain and diarrhea. Influenza, on the other hand, usually features high fever and body aches and only rarely features vomiting as a symptom.

There is no current norovirus vaccine in the U.S., so Belcher says the best way to avoid norovirus is good food preparation and hand washing.