Dec 26, 2023 - Health

New COVID strain quickly becomes most dominant in U.S.

COVID-19 variants in the U.S.
Data: CDC; Chart: Kavya Beheraj/Axios

The fast-spreading COVID-19 variant known as JN.1 is now the most prevalent in the U.S., accounting for more than 44% of cases as the virus expands domestically and internationally.

The big picture: JN.1's surge suggests it's either more transmissible or better at evading our immune systems than other strains in circulation, per the Centers for Disease Control and Prevention. But it's too early to tell how much it will drive an increase in infections or hospitalizations this winter.

Driving the news: JN.1 estimates shot up from 21.3% to 44.2% over the two weeks ending Dec. 23, according to the CDC, which noted the variant is showing up in more travelers and wastewater surveillance.

  • It was by far most prevalent in the Northeast, accounting for 56.9% of the cases in the Department of Health and Human Services' Region 2, which comprises New York, New Jersey and U.S. territories in the Caribbean.

The CDC said updated vaccines and existing tests and treatments still work well against the variant. Because it doesn't appear to pose additional risks, CDC said it was not changing its recommendations, which include getting updated vaccines and testing if respiratory symptoms arise.

  • The World Health Organization last week classified JN.1 as a separate variant of interest but added the additional public health risks it poses is low.

Between the lines: Increased holiday travel and waning immunity from prior COVID infections and vaccinations is setting up many people up for another round of disease.

  • Even if the symptoms aren't severe, enough viral spread could put a significant burden on health systems that also are grappling with a surge in other respiratory viruses including influenza, pneumonia and RSV.
  • COVID hospitalizations were up 10.4% in the most recent week, while flu activity was classified as "very high" in 10 states for the week ending Dec. 16.

What they're saying: JN.1 "may not result in a spike of hospitalizations, but it's definitely adding a significant burden of infections and subsequent risk of long COVID," Eric Topol, executive vice president of Scripps Research, wrote on X.

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