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 infections jumped a stomach-turning 159% last month compared to the same span last year in NYC, where flu cases are also up nearly 25% so far in 2025, city Department of Health data reveal. There were 1,264 norovirus cases last month in Gotham, compared to 488 in December 2023.

Rates of norovirus in that CDC system have reached levels at or above last season's peak in all regions of the country. Norovirus test positivity rates look to be the worst in the Midwest, in a grouping of states spanning Kansas through Michigan.

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.

Don gloves. It is necessary to wear gloves while cleaning during and after a bout of norovirus, and to wash your hands after removing and disposing of the gloves. “Even if you are wearing gloves, wash your hands for a full 20 seconds with soap and water after cleaning,” Ek says.

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.

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

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.

"It is too early to tell if this strain is associated with more severe norovirus disease but likely lower population immunity is the reason for the early surge of an otherwise seasonal increase of this virus," Jan Vinjé, head of the CDC's CaliciNet system, told CBS News in an email.

Although individual norovirus cases aren’t reportable in Oregon, outbreaks of norovirus are, and our “norovirus data year” starts in August and runs through the following July. This season, through the end of December Oregon recorded 29 norovirus outbreaks. (An outbreak is defined as two or more cases stemming from the same confirmed exposure).