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‘Double mutant’ coronavirus variant surfaces in Bay Area. Here’s what we know

The Bay Area has yet another coronavirus variant to contend with.

Through genomic sequencing, the Stanford Clinical Virology Lab has identified and confirmed one case of an emerging variant that originated in India, said Lisa Kim, a spokesperson for Stanford Health Care, on Sunday. Stanford is screening seven other presumptive cases; the location of the confirmed case was not disclosed.

The variant is being dubbed the “double mutant” because it carries two mutations in the virus that helps it latch itself onto cells. It could possibly be responsible for the troubling new surge in cases in India. Kim said it is not yet known if the variant is more infectious or resistant to vaccine antibodies.

Peter Chin-Hong, an infectious disease expert at UCSF, said it appears the variant could be more infectious because it accounts for 20% of cases in the heavily hit state of Maharashtra. Chin-Hong said cases have increased more than 50% there in the past week.

“It also makes sense that it will be more transmissible from a biological perspective as the two mutations act at the receptor binding domain of the virus, but there have been no official transmission studies to date,” he wrote in an email.

Chin-Hong said it’s too early to tell if the variant is more resistant to vaccine antibodies or can cause reinfections, but one of the variant’s mutations is similar to one found on the variants first detected in Brazil and South Africa, and the other mutation is also found in a variant first detected in California.

“This Indian variant contains two mutations in the same virus for the first time, previously seen on separate variants,” he said. “Since we know that the domain affected is the part that the virus uses to enter the body, and that the California variant is already potentially more resistant to some vaccine antibodies, it seems to reason that there is a chance that the Indian variant may do that too.”

He said so far no studies have confirmed any of this. Still, Chin-Hong said it appears this variant may be more regional, as the B.1.1.7 variant that originated in the U.K. is the more dominant strain in India. And while it’s not certain if the variant is resistant to vaccines, he is “optimistic” that vaccinations will work given what is known about their efficacy against the variants originating from South Africa and California.

The latest discovery adds to the list of worrisome variants that have made their way to the U.S., including the widely spreading B.1.1.7. variant, which is 50% more infectious. The P.1 strain that originated in Brazil and a variant from South Africa have both been found in the Bay Area, and both are believed to be somewhat resistant to vaccines.

There are many cases statewide of the variants originating in California that are more infectious and could possibly be resistant to vaccines, and ones from New York identified in Santa Clara County that could also be potentially vaccine-resistant.

Kellie Hwang is a San Francisco Chronicle staff writer. Email: [email protected] Twitter: @KellieHwang

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