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Scientists in California are increasingly worried about the state's "homegrown" coronavirus variant, with studies now showing that the variant is more transmissible than earlier strains and may be more resistant to current vaccines, according to news reports.

The variant, known as B.1.427/B.1.429, first emerged in California last spring but didn't show up on scientists' radar until this winter, when cases of the variant rapidly took off in the state, according to The New York Times. However, scientists weren't sure if the variant was indeed more contagious than previous strains or if it became more common simply by chance — for instance, through a few superspreading events.

In a new study, which has not yet been published in a peer-reviewed journal, researchers analyzed 2,172 virus samples collected in California between September 2020 and January 2021. They found that although the variant hadn't yet shown up in September, by January, it had become the predominant variant in California, with cases doubling every 18 days, The New York Times reported.

What's more, lab studies found that the variant was 40% better at infecting human cells compared with earlier strains, according to The New York Times. In addition, people who tested positive for the California variant had twice the viral load (or levels of the virus) in the nose and throat than people infected with other versions of the virus. This may mean that people infected with the California variant can spread it more easily than people infected with other strains, according to the Los Angeles Times.

The researchers said their findings mean that B.1.427/B.1.429 should be considered a "variant of concern" similar to the variants that emerged in the United Kingdom, South Africa and Brazil.