Studies find COVID-19 variant first found in California is more contagious

A coronavirus mutation first detected in California appears to be more contagious than earlier strains, according to two new studies.

One of the studies indicates rapid transmission through one San Francisco neighborhood in recent months, while another that tracked its spread across the state showed people infected with it have twice the typical number of viral particles in their bodies, according to The New York Times. Neither study has yet been published in a scientific journal.

“I’m increasingly convinced that this one is transmitting more than others locally,” William Hanage, an epidemiologist at Harvard’s T.H. Chan School of Public Health who was not part of the research, told the Times. “But there’s not evidence to suggest that it’s in the same ballpark as B.1.1.7,” the more infectious strain first detected in England.

Researchers including Charles Chiu, a virologist at the University of California, San Francisco, examined samples from positive tests in Californians to determine whether B.1.1.7 was present in the state. They discovered a previously unknown strain comprised about 25 percent of their samples, according to the Times.

The strain has been detected in multiple countries and at least 45 states, but only appears to be spreading widely in California.

Chiu and his colleagues went on to analyze 2,172 virus samples collected in California between September and January. During that period, it went from completely undetected to the most common variant in the state, and researchers now estimate cases of the specific variant double every 18 days.

A separate study indicated the variant was about 40 times as effective at spreading infection through human cells, and infected people produce about twice as large a viral load compared to the earlier variants.

However, while the variant is better at evading the body’s immune response, it appears to be far less effective against the vaccine than a separate South African variant.

“If we can get enough people vaccinated, we will be able to deal with these variants simply because we won’t have ongoing transmission,” Chiu told the Times.