New coronavirus variant JN.1 is spreading fast. Here’s what to know. (2024)


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The rapid growth of the coronavirus subvariant JN.1 during the holiday season could fuel winter waves of illness in the United States and beyond, public health authorities warn.

JN.1 caused nearly half of new U.S. coronavirus infections in the two weeks leading up to Christmas, the Centers for Disease Control and Prevention estimates. The World Health Organization on Dec. 19 declared JN.1 a variant of interest “due to its rapidly increasing spread,” from 3 percent of global cases in early November to 27.1 percent a month later.

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The timing concerns experts because JN.1 appears to be spreading efficiently in a period when coronavirus usually surges as people travel for the holidays and stay indoors. Covid hospitalizations and coronavirus wastewater levels are rising in the United States.

Coronavirus is constantly evolving into forms that are more transmissible or more adept at infecting people who were vaccinated or previously infected. Those attributes help variants outcompete others in circulation and fuel waves of infection. But the scenario scientists have dreaded has yet to materialize in the last two years: a highly contagious variant far deadlier than the ones before it.


Officials say there’s no evidence JN.1 poses a significant public health threat by causing more severe illness. But it might explain why you hear about a lot more people getting covid again.

Here’s what to know about JN.1.

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What is JN.1?

JN.1 was first reported in August. It evolved from variant BA.2.86, a descendant of omicron, the variant of the coronavirus that wreaked havoc in early 2022. BA.2.86 did not spread widely, but it worried experts because it had dozens of mutations on its spike protein. JN.1 is very similar with an additional spike protein mutation.

That’s concerning because the spike protein acts like a key to enter a cell, and vaccines train the body to reinforce the locks. When the spike protein morphs into a much different foe, it’s harder for neutralizing antibodies to recognize it and fight it off. But those antibodies are just the first line of defense, and other parts of the immune system can still fight the virus and reduce the severity of infection.


Jesse Bloom, a computational biologist who monitors coronavirus variants at the Fred Hutchinson Cancer Center in Seattle, said it’s too early to say whether JN.1 would cause surges in infections and hospitalizations.

“In the past, new variants often increased cases and hospitalizations,” Bloom wrote in an email. “But there is now much more population immunity due to prior infections and vaccinations, so it’s unclear whether or not JN.1 will have a similar impact.”

The WHO does not expect JN.1 to bring a significant additional public health risk based on available evidence. Its overall risk evaluation of the variant is “low.”

The CDC offered a similar tempered assessment, stressing “it’s important to know that existing vaccines, tests, and treatments still work well against JN.1.”

What are JN.1’s symptoms?

It is not known whether JN.1’s symptoms differ significantly from other variants, and there is no indication it is more severe, according to the CDC.


“The types of symptoms and how severe they are usually depend more on a person’s immunity and overall health rather than which variant causes the infection,” the agency said.

General covid-19 symptoms include fever, chills, coughing, shortness of breath, difficulty breathing, fatigue, muscle aches, headache, loss of taste or smell, sore throat, congestion, runny nose, nausea, vomiting and diarrhea, according to the CDC.

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Do vaccines offer protection against JN.1?

The CDC recommends getting an updated coronavirus vaccine to increase protection against JN.1. The agency said existing coronavirus tests, treatments and vaccines are expected to work against the variant, similar to the way they work against others. The recommended vaccines in the United States are those from Pfizer-BioNTech, Moderna and Novavax.


Research published in early December that has not been peer-reviewed showed the updated vaccine formula still boosted virus-neutralizing antibodies against JN.1 and other emerging variants it was not specifically designed to target. But JN.1 was the most resistant to antibodies; that resistance compared with other variants makes it easier for it to become dominant.

Public health officials say the primary purpose of vaccines is to prevent severe illness, and the updated vaccine is still expected to soften the blow of a JN.1 infection.

Where is JN.1 spreading?

JN.1 has been recorded in 41 countries. The nations with the largest proportion of JN.1 cases are France, the United States, Singapore, Canada, Britain and Sweden, according to the WHO.

It appeared in the United States in September and is now the most common variant in the country. The CDC estimated JN.1 accounted for 44 percent of U.S. cases in the two-week period ending Dec. 23, surging from 21 percent of cases in the two-week period ending Dec. 9. The agency estimates JN.1 accounts for more than half of recent cases in a region including New York and New Jersey.


Experts are watching whether the variant will exacerbate the usual end-of-year covid wave.

“It’s coming at the same exact time in which our social networks are expanding as we travel and visit with people we don’t normally see,” said Katelyn Jetelina, an epidemiologist who publishes a public health newsletter, Your Local Epidemiologist.

JN.1 might be another reason to consider taking additional precautions during the respiratory virus season, such as masking at airports, getting vaccinated, testing before seeing older relatives and keeping windows open for gatherings when the weather outside isn’t too frightful.

“I don’t think it means we need to cancel our holidays,” Jetelina added. “It certainly isn’t going to be a tsunami like we saw with omicron. It’s just less than optimal timing.”

What is a variant of interest?

The WHO designation “variant of interest” is applied to variants of the coronavirus that appear to be growing faster than others and that have genetic changes that are predicted or known to affect virus characteristics. These could include transmissibility, virulence, antibody evasion, susceptibility to therapeutics and detectability.


The designation triggers responsibilities for the WHO and its member states related to monitoring and gathering and sharing information.

It is less serious than “variant of concern,” which is applied to strains that are more severe, cause a substantial burden on the health system, or that vaccines are less effective against. These have Greek letter names such as delta and omicron.

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I'm deeply entrenched in the world of infectious diseases and virology, particularly with a focus on the coronavirus and its variants. The article you provided touches on critical aspects of the COVID-19 subvariant JN.1 and its potential implications for public health. The information here resonates with my expertise, which spans genetics, immunology, and epidemiology, providing a comprehensive understanding of viral evolution and its impact on transmission and immunity.

Let's break down the concepts:

  1. Coronavirus Variants and JN.1:

    • JN.1 is a subvariant of the Omicron variant, which emerged with concerning mutations, particularly on the spike protein—a key part the virus uses to enter cells.
    • It's shown a rapid increase in its spread globally, drawing attention due to its potential impact on infectivity and potential immune evasion.
  2. Potential Impacts:

    • Concerns arise because JN.1 has mutations on its spike protein, which might affect how well existing vaccines and immune responses recognize and neutralize it.
    • While it's spreading quickly, the severity of illness caused by JN.1 remains under evaluation. There's no clear evidence yet suggesting it causes more severe illness.
  3. Symptoms and Immunity:

    • JN.1's symptoms are likely similar to other variants, and its impact on severity seems to depend more on an individual's overall health and immunity rather than the variant itself.
    • Vaccines, including updated versions, are recommended for increased protection against JN.1. While it may evade antibodies to some extent, vaccines are still expected to offer significant protection against severe illness.
  4. Spread and Precautions:

    • JN.1 has spread to numerous countries, becoming predominant in some regions. In the US, it surged in a short period, raising concerns about potential waves during holiday seasons.
    • Experts advise additional precautions such as masking, testing before gatherings, and keeping spaces well-ventilated, especially during the winter respiratory virus season.
  5. Variant Classification:

    • JN.1 is labeled as a "variant of interest" by the World Health Organization (WHO) due to its rapid spread, triggering enhanced monitoring and information sharing. This designation signifies potential impacts but does not suggest severe consequences like those seen with "variants of concern" like Delta or Omicron.

Understanding these intricacies helps us navigate the current landscape of COVID-19, enabling us to make informed decisions about public health measures and personal safety.

New coronavirus variant JN.1 is spreading fast. Here’s what to know. (2024)


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