As Norovirus cases rise, here’s what to know about this year’s spread — and how to protect yourself

Norovirus has been rising in the U.S. since as early as mid-October, especially in states like Louisiana, Michigan and Indiana, according to data from WastewaterSCAN.

A nasty, highly contagious virus is spreading across the country ahead of the holiday season — and it’s not the flu or Covid.

Norovirus, also called the “winter vomiting disease,” has been rising across the nation since as early as mid-October, especially in states like Louisiana, Michigan and Indiana, according to data from WastewaterSCAN, an academic program through Stanford University in partnership with Emory University.

With data through Nov. 21, Amanda Bidwell, scientific program manager for the WastewaterSCAN program, said norovirus wastewater concentrations have increased nationwide by 69% since October.

“Right now, we’re in the high category for norovirus at the national level,” she said. Rates are high in the Northeast and Midwest region, according to wastewater data.

Rates are currently lower compared to last year’s spike, which was overwhelmingly caused by the variant GII.17, which may have mutated to become more contagious, experts said. Between August and November 2024, there were 235 reported norovirus outbreaks, according to the Centers for Disease Control and Prevention.