Adults who remain at risk include the 3% of the U.S. adult population that takes immunosuppresive drugs, children under 5 who are too young to be vaccinated, and people who have diabetes, are obese or are over 65.

“That’s a big chunk of the population,” said John Schwartzberg, an infectious-disease expert at the University of California at Berkeley. “Almost every time we have a surge, we lift our mandates too soon,” Schwartzberg said. “That’s what we’re doing now, I think.”

Charis Hill, a disabled, immunocompromised activist in Sacramento, says seeing 70% of people maskless at the store this week was “terrifying.” California’s rule change means Hill will stay sequestered. “I can’t leave my home without being filled with terror,” Hill said.