A new strain of COVID-19 is circulating in California, and scientists say it’s showing up in wastewater samples across the Bay Area as concerns grow over limited access to vaccines.
The variant, known as NB.1.8.1, was first identified in China last month and has since been detected in the U.S. and Europe. Researchers at Stanford University confirmed its presence in California’s wastewater, a key method of tracking the virus.
“It’s been reported in Europe, it’s been reported here in the U.S., and we’ve seen it in our wastewater here in California — so it’s around,” said Dr. John Swartzberg, an infectious disease and vaccinology expert at the University of California, Berkeley.
While early indications suggest NB.1.8.1 is not more severe than earlier variants, scientists believe it may be more contagious.
“It appears to bind more strongly to receptor sites on our cells,” Swartzberg said. “That may make it more transmissible, which would not be good news.”
COVID-19 case numbers have remained relatively low in 2025, but public health experts caution that the virus may resurge in the fall and winter.
“During the respiratory virus season, we could see more infections with circulating variants, leading to more hospitalizations and deaths,” said Dr. Arthur Reingold, a professor of epidemiology at UC Berkeley.
The emergence of the new strain comes amid controversy over recent federal vaccine guidance. U.S. Health and Human Services Secretary Robert F. Kennedy Jr. this week removed COVID-19 vaccines for pregnant women and healthy children from the Centers for Disease Control and Prevention’s recommended immunization schedule.
Swartzberg warned that the decision could undermine protections for infants.
“If you’re vaccinated during pregnancy, the antibodies pass through to the baby and can protect them for up to six months,” he said. “That protection is being lost by this decision.”
Despite the changes in federal guidance, some health professionals are urging the public to continue getting boosters.
“I personally am going to get a booster,” Reingold said. “I recommend my friends and family do the same.”
Yesterday, Health Human Services Secretary Robert F. Kennedy ended the recommendation that pregnant women and children should be vaccinated against COVID-19. There is no word yet whether these developments will cause a reversal of his guidance.
