New data from the Centers for Disease Control and Prevention indicate that the California strain accounted for 13% of all coronavirus samples that were genetically sequenced as part of a new federal program in late February. An additional 7% of the samples were the strain from the U.K.
Both versions of the virus have scientists and health officials on edge because they spread more readily than their predecessors and seem to be less vulnerable to some of the medicines used to treat COVID-19. The California strain has also shown signs of resistance to the current crop of COVID-19 vaccines.
Indeed, studies have found it to be 20% more transmissible than other variants in broad circulation. Its enhanced powers of transmission, ability to short-circuit the effectiveness of treatments, and ability to compromise the effects of vaccine prompted the CDC this week to declare the homegrown strain a “variant of concern.”
Known to scientists as B.1.427/B.1.429, it exploded in California throughout the fall and early winter as the state battled a deadly holiday surge. It now predominates in its home state and two of its neighbors. As of mid-February, it accounted for 52% of sequenced samples from California, 41% of samples from Nevada and 25% of samples from Arizona, CDC data show.
But the U.K. strain is giving it a run for its money — with a projected impact that ranges from uncertain to deeply worrisome.
In January, researchers at the CDC predicted that the U.K. variant would become the dominant one in the U.S. by March. Epidemiologist Summer Galloway, the lead author of that report, said Wednesday that it probably accounts for 20% to 30% of the samples being sequenced today.
The CDC does not have an equivalent estimate of how widespread the California variant is, Galloway said.
What the genetic sequencing data do show is that the U.K. variant, known as B.1.1.7, is making inroads across the country and has fueled a handful of local outbreaks. Its documented presence has grown from 76 cases in 12 states in early January to 4,686 cases in all 50 states and the District of Columbia by late February.
The B.1.1.7 variant is thought to be as much as 50% more transmissible than other widely circulating variants, and a study published this week in the journal Nature suggests it is 61% more likely to cause severe disease or death.
At the same time, however, many state governors are loosening restrictions on mask wearing, restaurant dining, and attendance at large gatherings.
The new CDC findings prompted Dr. Eric Topol, director of the Scripps Research Translational Institute in La Jolla, to declare that the California variant “is on its way to obsolescence.”
The fact that the U.K. variant’s transmission rate is higher than that of the California strain means the latter “will be quickly crowded out by B.1.1.7,” he…