NB.1.8.1: New contagious COVID-19 variant now circulating in California, health experts warn: Here’s what to know

SAN FRANCISCO (KGO) — Scientists at Stanford have detected a new COVID variant that experts say is already evident in wastewater samples in California, even as access to vaccines is restricted.

COVID-19 is still evolving and scientists are keeping close tabs on NB.1.8.1, a substrain detected in China last month, and now is circulating in the Bay Area.

“It’s been reported in Europe and it’s been reported here in the U.S. and we’ve seen it here in our wastewater in California, in wastewater, so it’s around,” said Dr. John Swartzberg, a UC Berkeley expert in infectious diseases and vaccinology.

Experts say the good news is this strain does not appear to be more virulent, but it looks like it is more contagious.

“It appears to be able to attach to the receptor sites on our cells more avidly, with greater ability which may mean it’s more transmissible which would not be good news,” Dr. Swartzberg said.

COVID numbers have been low in 2025 so far, but that could change in the coming months.

“Come the fall and next winter, respiratory season if you will, that we will see a resurgence, more people getting infected with the circulating variant, more people hospitalized and more people dying,” said UC Berkeley epidemiology professor Dr. Arthur Reingold.

That could be factored into decisions about an upcoming COVID booster, even as vaccine access is being restricted with the Health and Human Services Secretary Robert F. Kennedy Jr. now removing the vaccine from the CDC’s immunization schedule for pregnant women and healthy children.

“We know if you’re vaccinated during pregnancy, those antibodies mom develops pass through to the baby, and protects infants up to about 6 months of age from COVID, so all of this protection is being lost by this decision,” Dr. Swartzberg said.

“I personally am going to get a booster, I recommend my friends and family get the booster,” Dr. Reingold said.