Overview
- CDC data show national norovirus test positivity at 11.69% for the week ending Nov. 22, with the western U.S. higher at 14.08%.
- Los Angeles County reports increasing norovirus concentrations in wastewater, while state officials say overall California levels are still low but trending up.
- WastewaterSCAN readings in Michigan have climbed since mid-October, with five of six monitored sites—Jackson, Jenison, Mt. Pleasant, Traverse City, and Warren—classified as high.
- Michigan clinicians and parents report rapid within-household spread and short illness duration of roughly two to three days, with emphasis on staying hydrated, especially for children.
- Doctors caution that the GII.17 subvariant could drive more illness this season, and experts advise thorough handwashing and surface cleaning because standard hand sanitizer is ineffective.