The coronavirus variant first seen in Los Angeles in July now accounts for about 44% of new infections in Southern California and more than a third of new infections across the state, the researchers reported on Thursday.
In addition, the variant has spread to the United States and six countries around the globe, according to the study published in the Journal of the American Medical Assn.
“It remains uncertain” whether the genetic changes that characterize the fast-changing variant have improved its ability to transmit from person to person or to make infected people sicker, a team at Cedars-Sinai Medical Center in Los Angeles acknowledged in the JAMA Report. But the rapid spread of the virus in California is cause for concern, they wrote.
The local variant is distinct from other versions of the virus present in the USA, including strain B.1.1.7 from the United Kingdom and strain B.1.351 from South Africa. But, like these new strains, this variant is defined by several mutations in the virus’s spike protein, the “coupling mechanism” that the virus uses to attach to human cells.
One of the five mutations of the California variant, known to scientists as L452R, may alter a particularly critical part of the spike protein called the receptor-binding domain.
A study conducted last year by researchers at Howard University found that the mutation helps the virus to bind more tightly to human cells. Therefore, it has the potential to increase the transmission of the virus.
At both Cedars-Sinai and UC San Francisco Medical Center, samples of the new variant are being tested in an effort to detect whether its altered genetic makeup has given the virus new powers to spread or become ill.
“New variants do not always affect the behavior of a virus in the body,” said Dr. Eric Vail, one of the study’s senior authors.
But how it took off amid a calamitous wave of new infections in Southern California and why three of the five changes in its genetic code involve the spike protein, is of particular interest, said Vail, molecular pathologist at Cedars Department of Pathology and Laboratory Medicine from Sinai.
Its growing share of cases in California is also threatening, the study authors said.
Although the variant was barely detectable in early October, it accounted for 24% of the approximately 4,500 viral samples collected across southern California in the last weeks of 2020, and 18% of samples across the state. Less than a month later, his share of new infections had increased.
From January 1 to January 22, the variant was responsible for 44% of the coronavirus samples collected in Southern California and 35% of the samples from across the state.
In assessing the likely impact of emerging variants elsewhere, scientists saw trends like this as evidence that a new genetic variant has gained a competitive advantage over others already in circulation. One explanation would be an increase in transmissibility.
“If you look at the numbers, they suggest that [the California variant] it’s probably more infectious, ”said Jasmine Plummer, a Cedars-Sinai researcher who led the study with Vail. But because other factors may have contributed to its growing presence, “we need to do more studies” to confirm the suspicion, she warned.
Shaolei Teng, a Howard University biologist who led a team that explored the effect of the virus’s genetic changes, said the variant’s L452R mutation clearly improved its ability to bind to human cells. Most likely, he said, the change also makes it easier for the virus to enter cells – a crucial step in the replication process.
The mutation is “favorable to the virus and may be the reason why it has become dominant in California,” said Teng.
Furthermore, the variant started to travel widely. It was detected in Alaska, Arizona, Connecticut, Georgia, Hawaii, Maryland, Michigan, New Mexico, Nevada, New York, Oregon, Rhode Island, South Carolina, Texas, Utah, Washington, Wisconsin, Wyoming and Washington, DC
It also made its way to Australia, Denmark, Israel, New Zealand, Singapore and the United Kingdom.
“The appearance of this and other new variants is likely to be a common occurrence until the spread of this virus is reduced,” wrote a team from the National Institute of Allergy and Infectious Diseases in an editorial accompanying the study. “This emphasizes the importance of a global approach to vaccine surveillance, tracking and implantation.”
Plummer said that Southern California travelers probably carried the new variant with them to other states and countries.
Los Angeles International Airport has long been among the busiest travel hubs in the U.S., ranking second in total passengers boarded in 2019, according to the U.S. Department of Transportation. It is the main gateway to the USA to a number of foreign destinations, including Australia and New Zealand.
Although air traffic in the United States fell during the pandemic, more than 4 million domestic and international passengers were still traveling through LAX in November and December, according to Los Angeles World Airports, which operates the airport.