US Norovirus Stays High as GII.17 Drives 75% of Outbreaks

2 articles · Updated · NBC News · May 29

Wastewater surveillance shows norovirus at “high” levels across much of the U.S., with concentrations still rising in the Northeast and a notable outbreak signal in the San Francisco Bay Area.
GII.17, a mutated strain that partially evades prior immunity, became the dominant U.S. variant in 2024-25 and caused about 75% of outbreaks, helping the virus spread even though experts say it is not inherently more contagious.
1,194 outbreaks were recorded by CDC’s NoroSTAT from Aug. 1 to May 7, down from 2,534 a year earlier and broadly in line with seasonal averages, suggesting wastewater may be catching illnesses that never reach formal reporting.
Up to seven other people can be infected by one patient on average, with late-spring travel, indoor crowding during extreme heat, contaminated food and shared surfaces all aiding transmission.
Most people recover within several days but can keep spreading the virus for up to two weeks; doctors advise oral rehydration, soap-and-water handwashing and EPA-registered disinfectants, noting antibiotics and many hand sanitizers do not work.

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