A new variant of the coronavirus has appeared in the city.
The strain, known as XEC, has become established in the United States, accounting for an estimated 5.7% of new infections over the past two weeks, the Centers for Disease Control and Prevention announced Friday.
“We don’t know if it’s going to have legs and skyrocket up the charts,” said Dr. Peter Chin-Hong, a professor of medicine and infectious disease expert at the University of California, San Francisco. “But it has features that could make it noteworthy.”
XEC has spread rapidly in parts of Europe in recent weeks and has caught the attention of experts. Still, much remains unknown about this stock.
Rick Bright, an immunologist and former director of the Biomedical Advanced Research and Development Authority, said: “This shows once again that the coronavirus is far from finished mutating, and there are still limits to how well vaccines can control it.” I understand,” he said. of the Department of Health and Human Services.
Chin-Hong said the mutant strain is a so-called recombinant of two other strains, KS.1.1 and KP.3.3, which exchanged genetic information to form a third strain, XEC. He said it means that it has been done.
The CDC says overall coronavirus levels remain high in the United States, but levels of the virus in wastewater appear to be on the decline after peaking in August.
Are XEC variants more contagious?
Bill Hanage, an epidemiologist and deputy director of the Center for Infectious Disease Dynamics at Harvard’s T.H. Chan School of Public Health, said there is still no evidence that the XEC variant is much more transmissible than those currently in circulation. .
“I would have liked to have seen the outbreak spread to more places by now to be sure it was more contagious,” Hanage said. “From what we’ve seen, it’s not clear that it’s that much better than similar analogs,” he said, referring to other variants in circulation.
“It’s really a recent newcomer,” he added. “And we’re going to see a lot more kids in this city.”
XEC was first detected in May, but so far the number of infections has not doubled at an alarming rate, Hanage said.
“It’s not a particularly alarming doubling time,” he said.
Mark Johnson, a virologist and professor of molecular microbiology and immunology at the University of Missouri School of Medicine, said the XEC variant began in earnest in Germany and then spread to neighboring countries such as the Netherlands and France.
But this variant has only gained a strong foothold in a small number of countries, so success in these regions may simply be due to the right virus being in the right place at the right time. Johnson said there is.
This is a phenomenon known as the founder effect, Hanage said, adding that it is not yet clear whether the virus itself is more contagious or whether other factors, such as increased summer travel, are causing the spread. Ta.
“This is where XEC comes in and I’m sure it’s going to be important, but I’m not specifically putting money into it to ensure that XEC is fully taken over by the winter,” he said.
Hanage also said there is no evidence yet that this strain causes more severe disease, adding that this is unlikely given genetic mutations.
Are vaccines also effective against XEC?
XEC, like countless other products before it, is part of the omicron family. The variant is closely related to KP.2, the strain targeted by the latest vaccines from Pfizer and Moderna. And both XEC and KP.1 are descendants of the JN.1 strain targeted by the latest Novavax vaccine.
“I think there’s good reason to think you’ll get adequate protection from the boosters that are available,” Hanage said.
The part of the virus that antibodies bind to, known as the spike protein, is similar between these strains.
“I’m happy that the appearance hasn’t changed much,” Chin-Hong said. “It’s not like a brand new branch. That’s why I think the vaccine is still generally a good fit.”
Mr Johnson said KP.3.1.1, the main variant causing a surge in cases this summer, was also similar to the XEC variant, and people who had been infected recently may have increased immunity to the latest strain. said.
But Bright cautioned that clinical data is ultimately needed to determine how effective the updated vaccine is against the XEC variant.
“Until we start seeing clinical data on how well the mRNA vaccines and the Novavax vaccine provide immunity against this new variant, we won’t know with confidence how bad this season will be,” Bright said. I can’t do that.”
