CDC Officially Calls California Coronavirus Strains 'Variants of Concern'

The new strains may be up to 20% more transmissible and current treatments may not work against them.
Fabienne Lang

As of Tuesday 16 March, two coronavirus strains first discovered in California mid-last year have officially been moved to "variants of concern" by the U.S. Centers for Disease Control and Prevention (CDC).

These two strains, officially named B.1.427 and B.1.429, may be up to 20% more transmissible than others, and not as receptive to COVID-19 treatments, said the CDC. However, the Center has not mentioned if the strains are immune to the COVID-19 vaccines.

The CDC has three levels by which it documents viruses: variant of interest, variant of concern, and variant of high consequence. 

The variant of concern category, in which these two California strains are now placed, is outlined as "A variant for which there is evidence of an increase in transmissibility, more severe disease (increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures," per the CDC.

If strains are proven to significantly reduce vaccine effectiveness, they are moved to the variant of high consequence category. 

What this means in terms of treatment

The most prominent point of concern at the moment is seeing how these two strains react to COVID-19 antibody treatments, such as those developed by Eli Lilly in the U.S.

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At this stage, more research needs to be carried out before knowing whether or not treatments and vaccines don't work against these strains. 

The California strains were first detected in Los Angeles on July 20, 2020, reported Deutsche Welle, and then again in October in southern California. By December 2020, the strain accounted for 24% of all samples in Los Angeles. 

There have been causes for concern that these variants are spreading faster than other coronavirus strains, that they could lead to more severe cases of infection, and require more intensive care, hence the CDC's decision to place them as variants of concern.

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