What to Know About the ‘California Variant’

For social distancing and vaccination measures, the guidance is still to ‘stay the course‘

Photo: Margarita Cheblokova/Getty

The term “California variant” refers to a version of the SARS-CoV-2 virus that emerged last year with three new mutations compared with its parent strain, but this variant is really a global traveler. It earned its name when it cropped up in Southern California in July 2020. By November 2020, the California variant had turned up in six U.S. states. Before the end of January 2021, its reach had expanded across oceans, where it has been detected in New Zealand, Israel, Denmark, Singapore, and the U.K.

But with three new changes, this initial California variant may be a mutation overachiever. In the first two months of 2021, another one has arisen in the Golden State. But this time, it has only one of those three mutations.

Research that has yet to be peer-reviewed suggests that this single sequence change, called L452R, may be the one mutation to rule them all among variants currently running rampant worldwide. Analysis of a global virus database identified several others that have popped up on their own around the world, all bearing the L452R hallmark.

This single-mutation version is also, according to the same preprint study, the one that infected gorillas at the San Diego Zoo.

There’s a reason that L452R all by itself could be key, and that’s because it’s in the key the virus uses to enter a cell.

The viral protein carrying this change is the “spike,” a molecular key that the virus uses to unlock cells and enter them. The changes in each California variant may let the virus jiggle the key in that lock a little longer, increasing its chances of infecting the cell. Some researchers have hypothesized that this feature could make the virus more infectious, but no one knows for sure. It’s also possible that the change gives the virus cover against an immune attack.

No one knows either how effective current vaccines are against newly risen variants, but studies of approved vaccines were done where other worrisome variants have cropped up. The good news is that despite lower effectiveness with some versions of the virus, vaccination still offers protection. As Karin Michels, PhD, professor and chair of the department of epidemiology at the University of California, Los Angeles, Fielding School of Public Health, told USA Today on Wednesday, “A little bit less effective is not not effective.”

Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases at the U.S. Centers for Disease Control and Prevention, leads the agency’s Covid-19 vaccination efforts. On Tuesday she told Howard Bauchner, editor and chief of the Journal of the American Medical Association, that she’s not surprised to see this pattern where variants crop up and seem to dominate the viral landscape so quickly. Global efforts to sequence the virus genome and find these variants means we’re going to find more of them, she pointed out.

In the meantime, she said, everyone needs to continue “full steam ahead” with looking for variants while building momentum on the vaccination front. “One of the important things to know is that … wearing a mask, socially distancing, those things look like they work just as well against these variants,” she said.

“Right now, there is no reason to have any confidence,” she added, “that the variants will impact the effectiveness of the vaccine.”



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Emily Willingham

Emily Willingham


Journalist, author, Texan, biologist. I write All About Us (we=us), All About Adolescence (our longest growth stage), & All About Aging (we’re all doing it).