LOS ANGELES, Jan. 18 (Xinhua) -- The California Department of Public Health (CDPH) revealed that another new COVID-19 variant, which is different from B.1.1.7 first found in Britain, was increasingly detected in multiple counties throughout the state with experts warning that it may be resistant to vaccine.

According to a document released by the state's healthcare authority on Sunday, the variant strain known as L452R, which was first identified in Denmark in March 2020, showed up in California as early as May and had been circulating in the state, especially in Santa Clara County.

The L452R variant has been identified more frequently since November, the document said, adding that it is too soon to know how prevalent the variant is statewide, nationally or globally.

At genomic sequencing labs, the new variant went from being found in 3.8 percent of samples to about 25 percent within less than a month, according to Charles Chiu, a virologist and professor of laboratory medicine from University of California San Francisco.

The CDPH said it was common to identify variants of viruses and it was working with the Centers for Disease Control and Prevention (CDC), local public health departments and laboratory sequencing partners to learn more about the variant, including how it spreads.

Santa Clara County Health Officer Dr. Sara Cody admitted that the variant was identified in several large outbreaks in the county, noting that the fact is "a red flag" showing COVID-19 virus continued to mutate and adapt so that "we cannot let down our guard."

Chiu, who noted L452R contributed to an increasing proportion of COVID-19 cases, was also quoted as saying that the variant affected the spike protein of COVID-19 virus, so there's a chance the currently-developed vaccines would be less effective against it.

The vaccines being administered in the United States currently were designed to give people immunity by inhibiting the virus's spike protein.

An article published on Cell.com in September by a group of Chinese and Canadian researchers said L452R has "decreased sensitivity to neutralizing mAbs (monoclonal antibodies)," which are used in the currently-approved vaccines to inhibit connections between the spike proteins of the virus and infected cells.

"The data so far is very preliminary but it basically does raise the concern that there may be some impact on the vaccine," said Chiu. "I think that's the most uncomfortable saying -- certainly much more work needs to be done in the laboratory."

As of Monday, California has 2,973,174 confirmed cases of COVID-19, resulting in 33,593 deaths. The number of COVID-related deaths increased by 0.6 percent or 201 cases in the past 24 hours.