A pair of coronavirus variants first seen in California seem to replicate better in the noses of infected people, something that could explain their faster spread, researchers reported Thursday.
But tests of blood from people who had received either the Pfizer or Moderna vaccines indicates that while the variants are little less susceptible, the vaccines still protect people from them.
The team led by Dr. Charles Chiu at the University of California, San Francisco did in-depth sequencing of more than 2,000 samples from people who tested positive for coronavirus across California. They found the B.1.427/B.1.429 variants – closely related variants first seen in California – increased from no samples in September to half of all samples taken in January.
Examination of nose swabs showed there was twice as much virus in samples taken from people infected with the variants compared to people infected with older strains of the virus – an indication B.1.427/B.1.429 strains replicate better and something that explains why they would be more contagious.
But they are not as transmissible as the B.1.1.7 variant first seen in Britain — one that’s now the most common variant found in the US — the team also reported in the journal Cell.
Tests against blood taken from coronavirus survivors and people who’d been vaccinated showed the B.1.427/B.1.429 variants can partly evade the immune response. Blood from nearly 90% of recovered patients showed a reduced antibody response to the variants, and blood from half the vaccinated people did.
Better genomic sequencing is needed to stay on top of these variants, the team wrote.
“Although our findings suggest that the B.1.427/B.1.429 variant emerged as early as May 2020, the first cases of B.1.427 and B.1.429 in the US were not identified by sequencing until September 28, 2020, and July 13, 2020, respectively,” they wrote.
“Earlier identification and monitoring of the variant might have guided focused contact tracing efforts by public health to slow its spread, as well as enabled more timely investigation of its potential significance.”