SAN FRANCISCO – A possibly worrisome variant of the coronavirus first identified in India – so new that it has no official name – has been found in California by scientists at Stanford University.

Nicknamed the “double mutant” variant by the BBC and others, the variant is sparking concern among some scientists because it contains not just one, but two worrisome mutations in its genetic composition that have been identified among other variants of concern being tracked by the U.S. Centers for Disease Control and Prevention.

“We don’t know how those two mutations behave when they’re paired together,” Dr. Benjamin Pinsky, director of the Clinical Virology Laboratory at Stanford, said in an interview Monday.

The existence of the newly discovered variant was first disclosed by India’s government on March 24, Pinsky said, after a surge of coronavirus cases was detected in the nation’s second-most populous state, Maharashtra, whose largest city is Mumbai. The new variant is responsible for roughly 15% to 20% of new coronavirus cases there.

A day later, on March 25, the Stanford lab identified the same variant in a coronavirus sample taken from a patient in the San Francisco Bay Area.

“On the 25th, we actually got our sequence back and found that, ‘Wow, this is actually the same variant that they’re talking about,’” Pinsky said. “So this rapid spread across the globe is pretty impressive, and also a bit concerning.”

Why this new variant may be worrisome 

The Stanford lab identified one confirmed case of the new variant and seven presumptive cases among  samples  from patients in the Bay Area, Pinsky said.

None of the other variants being monitored by federal officials have the same combination of these two  mutations, known as L452R and E484Q, the latter of which is closely related to a more well-known mutation known as E484K.

The L452R mutation became well known in California as one found in the California variant (B.1.427/B.1.429), resulting in a strain that is believed to make the virus more infectious and might cause reduced immunity in people who have been vaccinated.

The E484Q mutation is closely related to the  E484K mutation, which has been found in  variants first identified in South Africa (B.1.351); Brazil (P.1 and P.2) and New York (B.1.526). The E484K mutation is also concerning because it might give the virus the ability to partly evade the immune system’s protective response among inoculated people or those who have survived a conventional COVID-19 illness.

“What we don’t know is how those [two mutations] will behave when they’re put in the same virus,” Pinsky said. “There’s a reasonable amount of information about those [two mutations] individually. But will it be worse if they’re together? We don’t really know how they’re going to interact.”

The Stanford lab routinely performs genetic analysis for coronavirus specimens among COVID-19 patients in the Bay Area. They screen for three worrisome mutations: L452R, E484K, and N501Y. The N501Y mutation – thought to increase the transmissibility of the coronavirus – is found in the U.K. variant (B.1.1.7), as well as the South African variant  and one of the Brazilian variants (P.1).

The Stanford lab was able to detect the new variant’s E484Q mutation, even though the lab is designed to detect only the closely related E484K mutation. “So it’s kind of fortuitous that we were able to identify this,” Pinsky said.

Variant highlights importance of vaccinations 

The emergence of the new variant underscores how important it will be  to quickly vaccinate as many people as possible. The best known New York variant, B.1.526, is believed to have emerged in the Washington Heights neighborhood in Manhattan and then quickly spread through  the city, Dr. Anthony Fauci, the nation’s top infectious diseases expert, said at a briefing last month.

One way variants can emerge is through the infection of a single person who has a compromised immune system, Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention, said in March.

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