A highly contagious covid-19 variant called XBB.1.5 is currently the leading cause of covid-19 infections in the United States, but there is no evidence that it causes more serious illness.
health
January 6, 2023
Illustration of coronavirus variants Joshimer Binas / Alamy Stock Photo
A new Omicron subspecies, called XBB.1.5, is now the dominant covid-19 strain in the United States, and may become so in other parts of the world.
The rate of covid-19 infections with XBB.1.5 (called the Kraken) is doubling almost every week in the United States, said Stuart Ray of the Johns Hopkins University School of Medicine in Maryland, which is the highest in the country. It’s the fastest-spreading variant. The U.S. Centers for Disease Control and Prevention (CDC) says more than 40% of covid-19 cases in the country are due to XBB.1.5, up from just 1% in early December I’m assuming. In the northeastern United States, 75% of cases may be XBB.1.5.
“It’s the most contagious subtype ever detected,” said Maria Van Kerkhov of the World Health Organization at a press conference on January 4.
So far, XBB.1.5 has been detected in 28 countries, including the UK and Australia, she said. Although the UK government has not officially reported the proportion of covid-19 variants, UK research institute The Wellcome Sanger Institute said in mid-December that XBB.1.5 accounted for 4% of the country’s cases. I’m guessing.
XBB.1.5 arose after two previous covid-19 variants exchanged genetic material while infecting the same individual, Ray says. Although similar in nature, it has several advantageous features, one of which may be an improved ability to bind and infect human cells.
XBB.1.5 also appears to be better able to evade immunity than previous variants due to changes in the spike protein, which is part of the vaccine-targeted virus. A preliminary study led by Can Yue at the Chinese Academy of Sciences in Beijing found that the XBB.1.5 variant had an enhanced ability to evade antibodies in blood samples taken from 116 of his people. All of them had previously had CoronoVac covid one of which he had 3 times. Two doses of -19 vaccine or mRNA vaccine and recovered from recent covid-19 infection.
However, this does not mean that the covid-19 vaccine does not offer protection against this rapidly spreading subspecies. Ray says there’s ample evidence that people are less likely to get seriously ill or die from covid-19 than people. “Antibodies against older strains are activated and enhanced by exposure to the current strain, even if he’s not a 100% match,” says Bruce Hirsch, of New York’s North Shore University Hospital. .
Bivalent boosters available in the US and UK, which target subvariants more similar to XBB.1.5, offer even better protection, says Ray. In the U.S., only about 15% of the population over the age of five received the latest booster, leaving much of the population vulnerable.
The good news is that many treatments for covid-19, including antiviral drugs such as Paxlovid, continue to be effective against XBB.1.5, says Ray. Precautions such as masking and improved indoor ventilation can also slow the spread of XBB.1.5, he says.
“Fortunately, what we are not seeing is a completely new virus,” Hirsch said. “This is the latest variant to be a little more efficient and more infectious.”
reference: bioArxiv, DOI: 10.1101/2023.01.03.522427
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