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A majority of Los Angeles County coronavirus samples analyzed this past week were “variants of concern,” public health officials said Wednesday.

The finding means there’s likely an uptick in variants circulating throughout the county, which could mean increased transmissibility and potentially more severe illness. Variants may also evade antibodies generated by COVID-19 vaccines, a study found.

Among the 73 specimens that were analyzed in labs this past week, the county’s public health department found that 63% of them were variants of concern:

  • 25 cases, or 34%, were the California variant of concern, also known as the B.1.427/B.1.429
  • 21 cases, or 29%, were the U.K. variant of concern, also known as B.1.1.7

“The fact that the majority of sampled specimens are variants of concern suggests that these variants are increasingly widespread in our community,” Public Health Director Barbara Ferrer said in a Wednesday media briefing. “It emphasizes the importance of adhering to safety measures, such as masking, social distancing and regular routine hand washing, to avoid increasing the chances that variants of concern, become more prevalent.”

L.A. County has yet to identify cases of the South African variant, or the Brazilian variant of concern known as P.1, she added.

There are however other “variants of interest,” which could become “of concern” and are known mutations being monitored. In the last week, these included eight cases of the New York variant, and one case of the Brazilian variant of interest, also known as P.2.

The presence of variants of interest indicates the transmission of mutated viruses from elsewhere in the world, Ferrer said.

It’s possible that the California variant “crowded out” some of the other variants of interest and variants of concern. However, there is not yet enough research done to know whether that is the case.

The California variant made up more than 50% of cases in the county during the peak of the winter surge, Ferrer said Monday. There is increasing evidence that the variant is likely more infectious, she added, which would help explain why there was such a rapid growth in cases during the surge.

“If that’s the variant that’s still in some ways dominating or still circulating in very high numbers here in L.A. County, it would be very easy for us to get back to a situation where cases go up,” Ferrer said.

Because the data is not from a scientifically randomly selected sample, health officials say they have to interpret the results very carefully.

But still, Ferrer said, “I think it’s probably very safe to say that there are more variants circulating now than there were earlier in the year.”

Under the Biden administration, there will be a national bank of information about variants that will allow various labs doing specimen sequencing to share information, she said, helping to better understand the circulation of the variants and the relationship between them.

Although the region still has a long way to go to establish herd immunity, the county is starting to see evidence that increasing COVID-19 vaccinations are beginning to help curb transmission. Since the beginning of 2021, the number of new infections has fallen each week following the unprecedented surge.