New COVID Variant JN.1 Could Disrupt Holiday Plans

Dec. 7, 2023 — No one planning holiday gatherings or travel wants to hear this, but the rise of a new COVID-19 variant, JN.1, is concerning experts, who say it may threaten those good times. 

The good news is recent research suggests the 2023-2024 COVID-19 vaccine appears to work against this newest variant. But so few people have gotten the latest vaccine — less than 16% of U.S. adults — that some experts suggest it’s time for the CDC to urge the public who haven’t it to do so now, so the antibodies can kick in before the festivities.

“A significant wave [of JN.1] has started here and could be blunted with a high booster rate and mitigation measures,” said Eric Topol, MD, professor and executive vice president of Scripps Research in La Jolla, CA, and editor-in-chief of Medscape, WebMD’s sister site.

COVID metrics, meanwhile, have started to climb again. Nearly 10,000 people were hospitalized for COVID in the U.S. for the week ending Nov. 25, the CDC said, a 10% increase over the previous week. 

Who’s Who in the Family Tree

JN.1, an Omicron subvariant, was first detected in the U.S. in September and is termed “a notable descendent lineage” of Omicron subvariant BA.2.86 by the World Health Organization. When BA.2.86, also known as Pirola, was first identified in August, it appeared very different from other variants, the CDC said. That triggered concerns it might be more infectious than previous ones, even for people with immunity from vaccination and previous infections. 

“JN.1 is Pirola’s kid,” said Rajendram Rajnarayanan, PhD, assistant dean of research and associate professor at the New York Institute of Technology at Arkansas State University, who maintains a COVID-19 variant database. The variant BA.2.86 and offspring are worrisome due to the mutations, he said.

How Widespread Is JN.1?

As of Nov. 27, the CDC says, BA.2.86 is projected to comprise 5%-15% of circulating variants in the U.S. “The expected public health risk of this variant, including its offshoot JN.1, is low,” the agency said.

Currently, JN.1 is reported more often in Europe, Rajnarayanan said, but some countries have better reporting data than others. “It has probably spread to every country tracking COVID,’’ he said, due to the mutations in the spike protein that make it easier for it to bind and infect.

Wastewater data suggest the variant’s rise is helping to fuel a wave, Topol said. 

Vaccine Effectiveness Against JN.1, Other New Variants

The new XBB.1.5 monovalent vaccine, protects against XBB.1.5, another Omicron subvariant, but also JN.1 and other “emergent” viruses, a team of researchers reported Nov. 26 in a study on bioRxiv that has not yet been certified by peer review.

The updated vaccine, when given to uninfected people, boosted antibodies about 27-fold against XBB.1.5 and about 13- to 27-fold against JN.1 and other emergent viruses, the researchers reported.

While even primary doses of the COVID vaccine will likely help protect against the new JN.1 subvariant, “if you got the XBB.1.5 booster, it is going to be protecting you better against this new variant,” Rajnarayanan said.

2023-2024 Vaccine Uptake Low

In November, the CDC posted the first detailed estimates of who did. As of Nov. 18, less than 16% of U.S. adults had, with nearly 15% saying they planned to get it.

Coverage among children is lower, with just 6.3% of children up to date on the newest vaccine and 19% of parents saying they planned to get the 2023-2024 vaccine for their children.

Predictions, Mitigation

While some experts say a peak due to JN.1 is expected in the weeks ahead, Topol said it’s impossible to predict exactly how JN.1 will play out.

“It’s not going to be a repeat of November 2021,” when Omicron surfaced, Rajnarayanan predicted. Within 4 weeks of the World Health Organization declaring Omicron as a virus of concern, it spread around the world.

Mitigation measures can help, Rajnarayanan said. He suggested:

  • Get the new vaccine, and especially encourage vulnerable family and friends to do so.
  • If you are gathering inside for holiday festivities, improve circulation in the house, if possible.
  • Wear masks in airports and on planes and other public transportation.

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