Omicron XBB.1.5 is growing faster than other sub-variants in the US
The Centers for Disease Control and Prevention on Friday revised down its estimate of how heavily subvariant omicron XBB.1.5 is circulating in the United States, although it continues to spread faster than other versions of Covid-19.
XBB.1.5 accounted for 27.6% of sequenced Covid cases nationwide for the week ended January 7, compared to 18.3% for the weekend ended December 31. The CDC previously reported that XBB.1.5 accounted for about 41% of the sequenced cases for the week ending December 31, more than any other variant.
Although the agency has revised down its estimate, XBB.1.5 remains the only Omicron subvariant currently showing significant growth in the US. It is second only to omicron BQ.1.1, which currently accounts for 34% of sequenced Covid cases in the US
XBB.1.5 accounts for more than 70% of sequenced cases in the Northeast US, which is often a frontrunner for the rest of the country.
People walk past a COVID-19 testing site in New York, the United States, on December 7, 2022.
Michael Nagel | Xinhua News Agency | Getty Images
The World Health Organization has described XBB.1.5 as the most transmissible version of Covid to date. Scientists say XBB.1.5 has a mutation that makes it bind better to human cells, potentially making it better at infecting humans than other variants.
dr Ashish Jha, who leads the White House Covid Task Force, said in a series of Twitter posts on Wednesday that the XBB.1.5 subvariant is likely more immune-avoidable and possibly also more inherently contagious because it binds more tightly to human cells .
Jha said it’s unclear if XBB.1.5 is more dangerous than previous variants. But dr Robert Califf, who heads the Food and Drug Administration, noted in a series of Twitter posts on Wednesday that cases are rising for now, with no evidence of increased disease severity.
Jha warned that people who last had a Covid vaccination before September or who had an infection before July are unlikely to have strong protection against XBB.1.5. Seniors who are not up to date with their vaccinations are increasingly vulnerable to serious illnesses, Jha said.
US health officials should soon have more data on how much protection the Omicron boosters offer against XBB.1.5, Jha said. Califf said the boosters should provide some protection against the subvariant based on studies looking at other subvariants in the same family, XBB and XBB.1.
“It is very likely that the current bivalent vaccines offer some protection against XBB, particularly in preventing serious illness and death,” Califf wrote on Twitter.
However, scientists from Columbia University found in a recent study that variants in the XBB family pose a serious threat to the Omicron boosters.
Weekly Covid cases have risen about 16% over the past week to 470,699, according to CDC data. According to the data, average daily hospitalizations have increased by 16% over the past week to more than 6,500. Weekly deaths were also up 8% the week before to more than 2,700.
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