A new report issued Wednesday by the Centers for Disease Control and Prevention reveals a variant of COVID-19 first identified in California may more frequently cause serious disease than other variants and may weaken antibody treatments.
The B.1.427/B.1.429 variant was identified in California in December and went on to become the predominant variant in the state, according to the New York Times. It has spread to many states across the country.
The report documents analysis by the Colorado Department of Public Health looking at cases of B.1.427/B.1.429 between Jan. 4 and March 20 in Colorado. They found the strain went from making up 3% to 4% of cases in late January to 20% to 22% of cases in early March.
B.1.427 and B.1.429 refers to two different lineage names, but the strains are closely associated and are often referred to as the California variant or the “West Coast strain,” according to the California Department of Public Health. The B.1.427/B.1.429 is associated with approximately 20% increased transmission. In comparison, the B.1.1.7 variant first identified in the United Kingdom is thought to have 50% increased transmission.
UCSF infectious diseases expert Dr. Peter Chin-Hong said the findings presented in the report are not surprising. “Californians should take strong note but not be too concerned immediately for a variety of reasons,” Chin-Hong, who wasn’t an author on the study, wrote in an email. “Most who would get severe disease have already been vaccinated which makes this a different context from before, and currently approved vaccines still work very well against this variant despite some overall diminished response. In general, vaccines generate many more antibodies than we need to protect against SARS CoV2).”
He added that what is concerning is unvaccinated individuals, especially those who are older or who have concomitant medical conditions, may be at a higher risk for severe disease and death with this variant. “This is a very different time for these individuals than one year ago,” Chin-Hong wrote.
The CDC report includes analysis of 327 B.1.427/B.1.429 specimens collected by the Colorado Department of Public Health across roughly three months. Among 211 patients with symptom information available, 91% were symptomatic and 14% hospitalized, the report said. There were eight (2%) deaths, and based on available data, seven (2%) vaccine breakthrough cases.
“Although Colorado variant data were derived from a convenience sample, when compared with national estimates of 85% symptomatic illness and 5% hospitalization rates among patients with positive SARS-CoV-2 test results, these data suggest that B.1.427/B.1.429 might more frequently cause discernible and severe illness than do nationally circulating lineages overall,” the study authors concluded.
The authors also wrote that B.1.427/B.1.429 may be resistant to the monoclonal antibody therapy bamlanivimab. Colorado’s department of health issued an advisory on March 22 recommending against monotherapy with bamlanivimab, and last month, the Food and Drug Administration revoked the Emergency Use Authorization for monotherapy with this product.
While the findings are concerning, a recent story in the LA Times suggests the presence of B.1.427/B.1.429 in California may have helped the state.
“Although the highly contagious U.K. variant (B.1.1.7) is believed to cause significant problems in the latest surge in Michigan, the California variant (B.1.427/B.1.429) is possibly keeping a lid on the U.K. variant in California,” the LA Times reported. “The California variant, though more contagious than the conventional strain, is less contagious than the U.K. variant — and if you had to choose between the two, the California variant is the better one to deal with.”