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Two new studies suggest that a variant of Covid-19 first discovered in California has spread rapidly in the state.
The findings come as the United States ramps up efforts to track and catalog various forms of the mutating virus and raise new questions about the circulation of the coronavirus in the country.
Here’s what we know so far:
What is the Californian variant?
The variant, called B.1.427 / B.1.429, first caught the attention of scientists in November 2020 and belongs to a lineage – a branch of the coronavirus family tree with similar mutations – that is believed to have emerged in may.
The variant has been detected in 19 countries, and throughout the United States, although limited surveillance has found it concentrated in California.
The variant has three mutations that change the shape of a protein, called a tip, on the surface of the coronavirus. Other variants, including those first discovered in the UK, South Africa and Brazil, also have mutations on their spike proteins. Researchers fear these changes will make it harder for the immune system to recognize and block the virus quickly.
Why are we talking about it now?
Scientists around the world have been tracking variants of Covid-19 by scanning samples taken from people infected with the virus. The United States has lagged behind other countries in this kind of surveillance – and still is. But some labs, including at the University of San Francisco, California, have recently redoubled their efforts to determine which variants are most common in the state.
While examining positive test samples for coronaviruses to see if B.1.1.7 – the variant first detected in the UK – was circulating in the state, USCF researchers realized that a variant different, local origin, in fact accounted for an increasing proportion of infections. Another Los Angeles team discovered that this variant was spreading there as well.
What does the research show so far?
There were two studies this week, both conducted by teams from UCSF. Neither has been peer reviewed or published in a scientific journal. The researchers said pre-prints of their work will be posted online in the coming days.
The first found that at the end of November, the B.1.427 / B.1.429 variant represented 16% of the samples sequenced in the Mission district of San Francisco, a low-income Latin American community in a city where many residents are also essential workers. In January, the variant represented 53% of the cases sampled.
The researchers found that after following 326 households, people in the same household as a person with the B.1.427 / B.1.429 variant had a 35% chance of being infected. People living with someone infected with another variant had a 26% chance of catching the virus.
“I would call it a very modest increase,” said Joe DeRisi, co-chair of Chan Zuckerberg Biohub, who has investigated the spread of the variant in San Francisco, of the transmission rates the study found. .
DeRisi’s team also found that the B.1.427 / B.1.429 variant did not correlate with more serious infections or a higher “viral load” – the amount of virus that builds up in the body.
Study results are limited – only 630 samples were sequenced in January and 191 in November, all collected from one neighborhood.
The second study was more pessimistic. He sequenced 2,172 samples from 44 counties in California and found that the B.1.427 / B.1.429 variant accounted for 0% of cases in September and about 50% of cases at the end of January.
This team also reviewed the medical records of 324 patients hospitalized for Covid-19 and found that 69 of those patients carried the B.1.427 / B.1.429 variant. These patients were more likely to be admitted to the ICU and more likely to die. The researchers hinted that the variant might be better at evading the immune system.
Charles Chiu, the infectious disease researcher and physician at UCSF who led the research, warned the findings were a warning. “The devil is already here,” he told the Los Angeles Times, and he and his team suggested that the Centers for Disease Control and Prevention (CDC) recognize B.1.427 / B.1.429 as a “worrying variant. – as the variants first discovered in the UK and South Africa have been tagged.
But this study also comes with caveats. Statistics suggesting that patients with B.1.427 / B.1.429 variants were more likely to die were based on the records of 69 patients who were admitted to hospital in the first place because they had very Covid-19. severe.
“If you only look at the sickest people, you’ll see something different than if you look at the population as a whole,” said DeRisi, who was not involved in the study of her colleagues.
Chiu did not respond to multiple requests for comment from the Guardian.
How worried should we be about this variant?
Neither study tells us exactly why transmission rates are higher. The virus could become more common by fluke, or because it is slightly more transmissible.
“I don’t think there is any doubt that this line is more and more common in California,” said William Hanage, epidemiologist at Harvard TH Chan School of Public Health. “But I think the amount of samples in California is not enough to fully define why. And I think we need to be wary of categorizing every locally emerging hopeful freak as a ‘worrying variant’. “
He noted that although the California variant has now become more common in the state, researchers believe it has probably been around since at least May. “You must be wondering why it has been around for so long and hasn’t taken the world by storm,” he said.
“I’m not panicked, and neither should you be,” said Monica Gandhi, infectious disease specialist at UCSF.
“It’s no surprise that we are seeing more variations,” she continued. “Viruses mutate, and often these mutations will allow them to become more transmissible.” It is the modus operandi of a pandemic virus. And it’s the job of scientists to track them and test whether new variants can better escape our immune system and vaccines.
But for now, Gandhi has said she isn’t particularly worried about B.1.427 / B.1.429, or the variant researchers reported this week in New York City. In both states, daily deaths and hospitalizations are declining despite the circulation of these new variants, she noted. “So far, none of these variations have evolved to the point that they can go completely through the masks, or overcome social distancing or any of the other public health measures we’ve implemented.”
“These emerging variants tell us that we need to be vigilant, that maybe we shouldn’t be making summer vacation plans today,” said Waleed Javaid, epidemiologist and director of infection prevention and control. Mount Sinai Hospital in New York. “But let’s wait and see before we worry too much.”
Will the vaccine protect people against these different variants?
The researchers found that vaccines may be slightly less effective against variants first found in South Africa, because mutations on the surface tip proteins make this variant less recognizable by certain antibodies that the immune system produces to find. the intrusive virus. Drug developers are now working to tailor vaccines to make them even more effective against these new, emerging variants.
But all the evidence indicates that those currently approved in the United States have been and will continue to protect people from the California variant.
“Experiments need to be done to test the efficacy of the antibody response elicited by vaccines against the B.1.427 / B.1.429 variants,” said Christopher Barnes, a biochemist at Caltech who has studied the vaccine response to variants. But, he added, “reduced responses are always effective because of the powerful immune response produced by vaccines.”
This is because Covid-19 vaccines cause the immune system to develop a range of defenses against the virus. Vaccines cause the body to create antibodies that attack the virus, but they also alert T helper cells, which can sound alarm bells about the invading infection and galvanize other cells to help fight it, and cells t killers – who find and destroy the virus. virus. In addition, special cells called memory b cells and memory t cells store information about the invading virus for months or years.
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