A more contagious mutation of the coronavirus is driving a new surge of cases in the United Kingdom, sending ripples of alarm around the world and triggering strict travel restrictions that could reach all the way to California and the Bay Area.
Prime Minister Boris Johnson imposed tough new lockdown measures, saying that the mutation is 70% more transmissible than existing strains, with British Health Secretary Matt Hancock saying the variant is “out of control” through London and southeastern England.
A similar strain was also detected in South Africa, accounting for 90% of the infections in the country.
“We haven’t seen anything related to a new strain yet into the state of California,” Gov. Gavin Newsom said during a press briefing Monday, but added that state officials are monitoring it closely.
Shannon Bennett, a microbiologist and chief of science for San Francisco’s California Academy of Sciences, said it is normal for coronaviruses to accumulate mutations over time, creating new strains.
Experts are worried because the new strain could prove to be more contagious and more aggressive.
“We’re concerned because of the unknowns,” said Dr. Mark Ghaly, California’s top health official.
Here is what we know so far.
Q: What is this new variant of coronavirus?
A: The new variant originated in southeast England, has nearly 20 mutations and is more contagious.
Called B.1.1.7, the strain also has been identified in Denmark, the Netherlands and Australia, according to the World Health Organization.
Bennett said her understanding is that there have been about 20 mutations, including a couple in the crucial spike proteins, which allow the virus to bind more strongly and enter human cells more easily.
“It’s a little bit more sticky than the COVID virus we’ve been seeing,” Ghaly said. “It seems to bind a little tighter and enter the cell of the human body more easily than the virus we have here in California.”
Microbiologists keep track of virus mutations and draw family tree-like charts, Bennett said, but the changes are generally benign. The notion that this strain is more transmissible is just conjecture at this point.
“They are inferring that it might be more transmissible because more people have this strain than did before, but you don’t really know whether it is more transmissible until you take it in a laboratory,” Bennett said.
Maria Van Kerkhove, the WHO’s technical lead for COVID-19, said during a Monday press briefing that the earliest cases of the new variant were discovered in the U.K. in September.
Q: How much faster does it spread?
A: Health experts in England believe the new variant is 70% more transmissible than other strains in circulation in the UK. B.1.1.7 is responsible for 80% of the current infections in London, according to Neil Ferguson at Imperial College London.
That means someone with the new strain could infect an average of 1.5 other people, rather than the 1.1 average for the earlier strain of the coronavirus, according to the WHO.
Bennett said the big fear is that the virus has adapted through natural selection a way to escape the vaccine or avoid the immunity that some people have developed, a notion she said is unlikely.
“There haven’t been enough people who have been infected and have immunity either naturally or by a vaccine for this virus to have selected to escape that,” Bennett said.
But it is possible, she said.
“This is something we want to watch for and it’s something we know how to watch for because we see it in influenza,” Bennett said. “We know it is possible, but it takes a long time for a virus to elude our immune response. So even if this strain evolved a couple of strains to elude one antibody, we have many many other antibodies. It takes many, many years of mutations for a virus to escape our immune response, but we will need to watch for it. And this virus evolves more slowly than influenza.”
Q: Will current vaccines work against the mutation?
A: Experts believe the current vaccines will be effective against the new strains.
Operation Warp Speed head Moncef Slaoui said that it is “very unlikely” that the vaccines currently available from Pfizer and Moderna would not work against the new strain.
“I don’t think there has been a single variant that would be resistant to the vaccine,” Slaoui said. “We can’t exclude it, but it’s not there now.”
Bennett said the two vaccines being rolled out now are called mRNA vaccines, where scientists put the genetic code into a host cell and then the host cell machinery translates the genetic code into viral proteins.
“The design of that kind of vaccine is much more tweak-able,” she said. “You can just tweak the code and pop it in and there you go.”
“We want to watch how the virus changes in the population so that it doesn’t erode our immune response,” Bennett said. “This will be unfolding over years. We will be able to see what’s coming and which strains might be able to produce an immune escape response, or evolve to escape our immune response.”
The vaccines that are being produced are generating powerful immune responses in people, she said, and because the virus evolves slowly, it is likely immunity will last for a long time.
“The take-home message is that all viruses evolve and accrue mutations over time. There are many, many variants and strains that bear watching, and that’s what we are doing. Here’s a variant or strain that appears to be more common, so let’s check it in the lab. I’m not going to say it's a lot of hullabaloos or much ado about nothing because it’s definitely a common strain that’s worth watching, but it is not worth panicking about. This level of variation is completely expected.”
Q: Is this new variant more lethal?
A: Evidence to date indicates the new variant is not any more lethal or any more dangerous than the normal coronavirus.
“So far, we don’t see any increase in disease severity or clinical picture, but those studies are under way,” Van Kerkhove said.
She said the strain found in South Africa contains a similar mutation to the one spreading in the U.K. but is a separate variant.
“Even though we’ve seen a number of changes and a number of mutations, none has made a significant impact on either the susceptibility of the virus to any of the currently used therapeutics, drugs, or the vaccines under development and one hopes that will continue to be the case,” WHO chief scientist Soumya Swaminathan said.
Q: How are public health officials responding?
A: Johnson announced a series of stricter coronavirus measures in the U.K., while countries around the world imposed tough travel restrictions on the country. The U.S. has not enacted any limits yet nationwide.
“This is a developing situation that we are monitoring closely,” the Federal Aviation Administration said in a statement. “We will continue to work with our government partners as the situation evolves.”
Newsom said California may impose a quarantine period for U.K. travelers.
“The last thing we want to do is let a new strain of COVID come and spread more rapidly across the state,” said Ghaly. “We’re watching this very closely.”
Q: Are current safety measures effective against the new variant?
A: Even though it is more contagious, currently coronavirus safety protocols should be effective in slowing the spread of the new strain.
“We’ve had dozens of mutations of this SARS-CoV-2 that causes COVID-19, this year alone,” Surgeon General Jerome Adams said Monday during an interview with Fox News. “What’s important for people to understand is this doesn’t change what we need to do. We need to wear masks, wash hands, watch our distances and wait on gatherings, and we need to get vaccines. Get vaccinated when those become available to us.”
Aidin Vaziri and Peter Fimrite are San Francisco Chronicle staff writers. Email: avaziri@sfchronicle.com or pfimrite@sfchronicle.com
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