Another worrisome coronavirus variant has made its global debut.
Scientists from the Indian state of Maharashtra identified a new strain two weeks ago that's linked to between 15% and 20% of cases there.
The variant has earned the somewhat ominous nickname "double mutant" because it has an unprecedented combination of two mutations that may help it both attach better to human cells and hide from the immune system.
Just 24 hours after Indian officials reported the variant, it also popped up in northern California. Researchers from the Clinical Virology Lab at Stanford identified this "double mutant" in a sample from a patients in the San Francisco Bay Area. They suspect another seven cases are linked to the variant.
"We don't know how those two mutations behave when they're paired together," Dr. Benjamin Pinsky, a Stanford virologist who helped discover the variant, told the LA Times.
But Dr. Peter Chin-Hong, an infectious-disease expert at the University of California, San Francisco, said panic about the variant is premature — and its nickname is a bit sensational.
"It suggests that it is doubly scary or doubly transmissible even compared to a variant that we know about, but there is no evidence to suggest that," Chin-Hong told Insider.
Plus, he added, many variants have multiple mutations.
An unprecedented combination of mutations
Scientists keep tabs on the coronavirus' evolution by genetically sequencing samples on a regular basis. Every variant has a unique genetic code peppered with mutations — that's how researchers can classify different strains.
Most mutations are innocuous, but sometimes, a combination of genetic tweaks emerge that helps the virus survive or spread better. The "double mutant" brings together two worrisome mutations in the same variant for the first time.
One mutation, known as L452R, helps the virus' spike protein bind more tightly to cells. That same mutation is also present in a variant first spotted in Los Angeles last fall. The other mutation — called E484Q — bares a "chilling" resemblance to a mutation found in variants from South Africa and Brazil, according to Chin-Hong. That tweak helps the variant evade detection by antibodies the body has developed in response to an infection with the original virus.
"There's a reasonable amount of information about those individually," Pinsky said of the two mutations. But he added: "Will it be worse if they're together?" We don't really know how they're going to interact."
No studies yet have found that this "double mutant" is deadlier than earlier versions of the virus, or that it can evade vaccines.
That said, some "early hallmarks" suggest the variant could be more transmissible, Chin-Hong said. In the last week, Maharashtra saw a 55% increase in infections. The Indian government says there's not enough evidence to link that surge to this variant, but epidemiology researchers at the Indian Institute of Public Health have suggested that it's the most likely explanation.
It's unlikely the new variant will come to dominate in California
While the discovery of yet another worrisome variant is concerning, it's not the variant that California in particular should be focused on, according to Chin-Hong.
"I do not at this time think that this 'Indian variant' will dominate the California viral landscape," he said, adding, "we already have two svelte and dastardly variants adept at transmission duking it out."
Those two are the variant found in the UK, which is linked to 851 cases in California, and another variant first spotted in Southern California. The California Department of Public Health reported last week that the latter accounts for more than 6,200 of the state's cases.
Chin-Hong also thinks the "double mutant" will have a harder time spreading in California because the state's winter surge of cases, coupled with rising vaccinations, have left fewer residents vulnerable to infection.
"This all acts as a force field — albeit temporary — against these new variants," he said.
