The Centers for Disease Control and Prevention revealed on Friday that it is now tracking a concerning new variant of COVID-19 in the United States, known as XBB, which has risen to account for about 3.1% of new infections in the United States. national scale.
The prevalence of the strain has increased so far in the northeast, according to the agency’s weekly estimates. More than 5% of infections in areas from New Jersey to Maine are linked to XBB, in this week’s CDC “Nowcast.”
XBB is responsible for a wide range of infections in some South Asian countries and accounts for an increasing share of viral sequences reported worldwide and among arriving international travellers.
Earlier this month, the CDC offered preliminary estimates suggesting that XBB potentially doubles in proportion approximately every 12 days. This could be faster than the current pace of the BQ.1 and BQ.1.1 variants which now dominate across the country.
However, the Biden administration’s top COVID officials and experts say theyXBB will pose a new threat on the scale of the Omicron variant first appearing a year ago.
“Where we’ve seen surges, they’ve seen it mostly driven by seasonality, people coming inside, spending more time with each other, but not specifically being driven by the emergence of a new variant,” said Ian Williams of the CDC. a meeting of CDC emergency response and preparedness advisors earlier this month.
XBB is one of many new bloodlines that displaced BA.4 and BA.5, the variant siblings of Omicron that had caused a surge in cases over the summer. As of this week, the CDC reports that BA.5 has fallen to less than 1 in 5 new infections nationwide and BA.4 is now virtually gone.
The strain’s arrival also comes at a time when most regions, including the northeast, are seeing relatively stable or slowing COVID-19 hospitalization rates.
About 3 in 4 Americans currently live in counties deemed at “low” COVID-19 community levels, the lowest level of precautions recommended by the agency, according to figures released Friday by the agency.
“However, there is a lot of fear that a new variant could emerge and start us over again. So there is a lot of work to make sure we are prepared and to think about it and watch if it emerges in the world, so we can prepare ourselves” , added Williams.
A “recombinant” strain
First named by scientists in September, XBB is believed to be a “recombinant” of two different Omicron sub-variants – BA.2.10.1 and BA.2.75 – which emerged earlier this year. This is the latest in a now-dominant host of strains carrying mutations that could evade major COVID-19 antibodies.
“There has been a rapid increase in XBB, but it doesn’t appear to be particularly more severe than other variants,” Derek Smith, director of the Center for Pathogen Evolution at the University of Cambridge, told CBS. News in an interview at the end of last month.
Smith helps lead the National Institutes of Health’s efforts to detect and analyze variants as they emerge, as part of an “Avengers-Like” program that spans several US federal agencies and outside experts.
“XBB, it caught our attention and was then prioritized, even though it was small numbers, because it had a number of different substitutions from the viruses currently circulating in the world. [receptor-binding domain]which meant it could be an escape variant,” Smith said.
NIH scientists early began ordering supplies to make mock-ups of XBB to test how it might evade immunity in the lab against other strains.
The data also now suggests that the new COVID boosters will at least offer improved protection against the strain.
A study published by Pfizer and BioNTech earlier this month, which has been published as a preprint and has not yet been peer-reviewed, found that their updated COVID reminder appears to be effective in triggering better antibody responses against an XBB strain.
However, the company’s scientists also said that it was one of the variants that had the worst neutralization of their shot.
“It’s not falling off the map, but it’s going down. So you can expect some protection, but not the optimal protection,” Dr. Anthony Fauci, the president’s chief medical adviser, said Wednesday during a briefing. a briefing at the White House.