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The Covid Omicron XBB.1.5 variant is rapidly dominating the US because it is more immunologically evasive and appears to be more effective at binding to cells than related subtypes, scientists say.
According to data released Friday by the Centers for Disease Control and Prevention, XBB.1.5 now represents 41% of new cases in the United States. Dec. The subvariant doubles as a share of cases every week until the 24th. In the last week, it has almost doubled from a spread of 21.7%.
Scientists and public health officials have been closely monitoring the XBB subtype family for months because the strains carry multiple mutations that can render Covid-19 vaccines, including omicron boosters, less effective and cause more progressive infections.
XBB was first identified in India in August. It soon dominates there and in Singapore. It evolved into a family of subtypes including XBB.1 and XBB.1.5.
Johns Hopkins virologist Andrew Pecos said XBB.1.5 differs from its family members because it has an additional mutation that binds better to cells.
“The virus needs to bind tightly to cells to be more efficient at getting in, and that helps the virus be a little more efficient at infecting people,” Pecos said.
Yunlong Richard Gao, a scientist and assistant professor at Peking University, published data on Twitter on Tuesday that showed that XBB.1.5, like the XBB.1 variant, not only effectively evades protective antibodies and is more immunogenic, but also better at binding. cells through a key receptor.
Columbia University scientists, In a study published earlier this month in the journal CellIt warned that the rise of subtypes such as XBB could “further compromise the efficacy of current Covid-19 vaccines and result in the rise of breakthrough infections and re-infections”.
XBB subtypes are also resistant to Evusheld, the antibody cocktail that many people with weakened immune systems rely on for protection against Covid infection, because they do not respond strongly to vaccines.
The scientists described the resistance of XBB subtypes to antibodies from vaccination and infection. The scientists found that the XBB subtypes were more effective at blocking protection from Omicron boosters than the BQ subtypes, which were more immunologically evasive.
Columbia study author Dr. David Ho agreed with other scientists that XBB.1.5 may have a growth advantage because it binds better to cells than its XBB cousins. Ho also said that XBB.1.5 is immune evasive like XBB and XBB.1, the two subtypes so far most resistant to protective antibodies from infections and vaccines.
Outgoing White House Chief Medical Advisor Dr. Anthony Fauci has previously stated that XBB subtypes reduce the protection provided by boosters against infection by “many folds”.
“You can expect some security, but not optimal security,” Fauci told reporters during a White House briefing in November.
Fauci said he was encouraged by the case of Singapore, which had a large surge of infections from XBB but did not see the same rate of hospitalizations. Pekosz said XBB.1.5, combined with holiday travel, could increase cases in the U.S. but he said boosters would prevent severe disease.
“It looks like the vaccine, the bivalent booster provides continued protection against hospitalization with these strains,” Pecos said. “This really emphasizes the need to get a booster, especially among vulnerable populations, to provide continued protection from serious disease with these new variants.”
Health officials in the United States have repeatedly called for assurances, especially for the elderly are up-to-date on their vaccinations and are being treated with the antiviral paxlovide If they have a breakthrough infection.