New California Variant May Be Driving Virus Surge There, Study Suggests

In late December, scientists in California began searching coronavirus samples for a fast-spreading new variant that had just been identified in Britain.

They found it, though in relatively few samples. But in the process, the scientists made another unwelcome discovery: California had produced a variant of its own.

That mutant, which belongs to a lineage known as CAL.20C, seemed to have popped up in July but lay low till November. Then it began to quickly spread.

CAL.20C accounted for more than half of the virus genome samples collected in Los Angeles laboratories on Jan. 13, according to a new study that has not yet been published.

“We had our own problem that didn’t cross over from Europe,” said Jasmine Plummer, a research scientist at Cedars-Sinai Medical Center in Los Angeles, who worked on the new study. “It really originated here, and it had the chance to start to emerge and surge over the holiday.”

There’s no evidence that CAL.20C is more lethal than other variants. And scientists have to conduct more research to determine whether CAL.20C is in fact more contagious than other forms of the virus.

But Eric Vail, the director of molecular pathology at Cedars-Sinai, said it was possible that CAL.20C is playing a large part in the surge of cases that has overwhelmed Southern California’s hospitals. “I’m decently confident that this is a more infectious strain of the virus,” Dr. Vail said. ...