What you need to know about norovirus

It's been the slowest start to the flu season in nearly three decades. That's the good news. The bad news: Another bug, called norovirus, is spreading all over.

CBS News medical correspondent Dr. Jon LaPook says it's a very nasty bug that causes nausea, vomiting, diarrhea, abdominal pain and fever.

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It's a food-borne illness -- spread person-to-person -- one person's hand to another person's hand. That's why you see these outbreaks in nursing homes and on campuses.

Twenty million Americans will get the virus, killing 800 people annually. If you have symptoms (vomiting, diarrhea, stomach cramps,) it's best to get rest and drink lots of fluids for dehydration. Antiviral medicine and a vaccine being developed.

Good hand washing is important in trying to keep from getting norovirus. You should wash your hands for 20 seconds. Dr. LaPook suggests singing "Happy Birthday" twice.

To learn more about norovirus, click on the video above.