CDC report says California variant may cause more serious illness - SF Gate

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.