The U.S. is seeing a "quad-demic" as cases of COVID-19, flu, RSV and norovirus spread at the same time. Experts said this is what you need to know.

Norovirus, also known as the stomach bug, is spreading across the U.S. Here's what to know about the contagious virus and how best to prevent an infection.

The cases mark the fourth norovirus outbreak on Holland America ships since early December, following others on its Eurodam, Rotterdam and Zuiderdam vessels. Other companies, including Cunard Line and Princess Cruises also saw outbreaks in recent weeks.

You can also get norovirus by touching objects or surfaces that are contaminated and then putting your hands in your mouth without washing them first. Hand-washing with soap and water is key, as hand sanitizer will not do the trick in the case of norovirus, experts say.

No. Hand sanitizer is simply not as effective against norovirus as it at killing other pathogens due to the virus's firm shell, Dr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center, told TODAY.com recently.

Illness typically lasts for one to three days but people can still be contagious after their symptoms have subsided.

CHICOPEE, Mass. (WWLP) – A new strain of Norovirus is impacting children and adults, and it’s spreading in our state. Respiratory illnesses continue to surge, that’s because it’s colder and more people are indoors allowing germs to spread, but it can be prevented.

According to the Minnesota Department of Health, there have been 76 reported outbreaks in December which is higher than in previous years.

New CDC data indicates a rise in cases of norovirus, often colloquially referred to as "stomach flu." Test positivity has spiked.

The brief but miserable symptoms have no treatment except hydration and rest. Doctors have several tips on how to stop the spread.

The U.S. is seeing a "quad-demic" as cases of COVID-19, flu, RSV and norovirus spread at the same time. Experts said this is what you need to know.