Norovirus—a highly contagious virus known for causing gastrointestinal distress—is making headlines this winter due to a sharp rise in cases and widespread outbreaks in Canada, the United States, and beyond.

A norovious outbreak at a California shelter housing Los Angeles fire evacuees has left 28 sick. The virulent illness norovirus spreads easily in close quarters, causing diarrhea, vomiting and stomach

Norovirus spreads very easily, and people may still be contagious even a week or two after recovering. The main danger is dehydration. No drugs cure norovirus.

The misery of the common stomach flu may be coming to an end. Pharmaceutical company Moderna has launched a large-scale Phase III trial that will test out a vaccine against norovirus, a frequent and sometimes dangerous source of food poisoning.

The virus, often colloquially referred to as “stomach flu,” saw the percentage of positive tests double during the first week of January compared to last year. Positive test percentages for cases of norovirus in the United States are double what they were at the same period a year ago,

Health officials are raising alarms about a significant increase in norovirus cases nationwide, including here in North Texas.

First came the fires. Then, there was ash and contaminated water. Now, some survivors of the Southern California wildfires are dealing with outbreaks of norovirus and other stomach ailments at a shelter set up to help evacuees.

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.

The Pasadena Public Health Department said they will support the American Red Cross and onsite medical teams following a Norovirus outbreak at the city's evacuation center.

Norovirus and its varying strains are nothing new, but health experts are seeing increased activity compared to other years.

"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.