A view of Transamerica Pyramid and buildings in San Francisco on Feb. 24, 2026.

For the past several weeks, a dizzying array of gastrointestinal and respiratory viruses have been circulating throughout the Bay Area, and San Francisco appears to be experiencing the worst of it.  

According to recent data from WastewaterSCAN, an organization that monitors viral traces in municipal wastewater, while rates of COVID-19 are low, rates of rotavirus, norovirus, human metapneumovirus (HMPV), influenza A and B, and RSV remain high (influenza A, however, is moderate in southeast San Francisco).  

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Though it’s still unclear why these viruses are so prevalent in San Francisco, health experts say changing vaccine recommendations could be partly to blame.

Rotavirus in particular, a gastrointestinal illness that can cause fatal diarrhea in small children, is much higher in 2026........

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