Alameda County reported on Tuesday six confirmed or suspected cases of a new, highly infectious variant of the coronavirus that was discovered in the United Kingdom.
The cases are the first of this variant tied to a specific Bay Area county. Stanford scientists had identified a handful of cases in the region last week, but declined to say what counties they were from.
The variant, known as B.1.1.7, has been identified in other parts of the state, mostly in Southern California, and 127 cases have been reported in California as of Monday, according to the Centers for Disease Control and Prevention. Nationwide, 541 cases of the variant have been reported in 33 states.
But public health officials say the variant likely is much more widespread and has not yet been identified due to lack of testing and genetic sequencing. They expect the numbers to increase as the state and country ramp up surveillance for new variants.
“What’s happening now is labs are increasingly doing more sequencing than was done before,” said Dr. Nicholas Moss, the Alameda County health officer. “People have cranked up that effort.”
Moss noted that the new variants so far don’t seem to be interfering with declining case numbers and hospitalizations in the region as the winter surge continues to wane. But he and other public health experts say they worry that the variants — either those already circulating or others that have not yet emerged or been identified — could lead to new waves of illness in the coming months.
“Whatever is going on with these variants, it hasn’t changed our trajectory for now. But it puts us on notice based on what we see in other parts of the world,” he said. “We’re glad to be in a period where we can reopen some things again and we’re grateful to have vaccines, but we need to be prepared for future surges.”
The six Alameda County cases are under investigation, Moss said. He did not yet have information about whether any of the individuals had traveled recently, but he believes they were all infected in the community.
He said the county also has identified cases of the variant identified in California earlier this month, known as B.1.429. Alameda County has not yet found cases of the variants identified in South Africa or Brazil, both of which are concerning because they may be able to partially evade vaccines.
The variant from the United Kingdom is thought to be roughly 50% more infectious than the original virus and thus able to spread faster and cause more illness. It may also cause more serious illness, though more research needs to be done.
Moss said he wasn’t surprised to find the B.1.1.7 and B.1.429 variants in Alameda County, given how many cases have been reported in other parts of the state.
“Any variant that’s been detected in any number of the larger counties in California, it’s a good bet it’s already present,” he said. “Even with travel restrictions and stay-at-home orders, our populations are interconnected.”
Erin Allday is a San Francisco Chronicle staff writer. Email: eallday@sfchronicle.com Twitter: @erinallday