A new variant of COVID-19 dubbed JN.1 is rapidly spreading and causing concerning spikes in cases across parts of Europe, Asia, and the Americas. First detected in late 2022, JN.1 has key mutations that allow it to partially evade prior immunity from vaccination and infection. While it may cause less severe illness for many, experts warn this new variant could still overwhelm healthcare systems.
JN.1 Now the Dominant Strain
JN.1 has swiftly become the dominant strain in several countries. Per recent data, it accounts for over 60% of new COVID-19 cases in France and around half of infections in the UK. Parts of Asia like Thailand have also reported JN.1 causing local surges.
In the US, Oregon health officials note JN.1 has grown to make up 62% of cases statewide. Its rapid rise led Oregon’s health authority to issue a warning this month about an expected influx in hospitalizations. So far, US monitoring has detected JN.1 cases in at least 28 states.
Table 1: Percent of COVID-19 cases caused by JN.1 variant
| Country/Region | % JN.1 cases |
| France | 62% |
| UK | 50% |
| Oregon, US | 62% |
Experts attribute JN.1’s success to its mutations allowing some evasion of immunity people have from past infection and vaccines designed against older forms of the virus.
“This ability to partly dodge prior immunity appears to be driving the variant’s rise around the world,” said Dr. Eric Topol, head of Florida’s Scripps Research Translational Institute, in a tweet Wednesday.
A “Fit” New Form Spreading Fast
Early lab studies show antibodies in blood samples from people vaccinated or previously infected are less effective at neutralizing JN.1 compared to past strains.
“The new mutations have made it more ‘fit’ – meaning it can spread faster despite immunity that exists,” said University of Oxford epidemiologist Dr. Anne Cori this week.
Cori’s modeling predicts that while many people have some protection against severe disease, JN.1 is still spreading fast enough to substantially drive up hospitalizations and deaths compared to a pre-JN.1 wave.
This forecast is already playing out in the upticks in case counts and hospitalizations in places like France and Oregon where JN.1 has grown dominant locally.
Less Severe Symptoms, But Still Dangerous
The good news is that JN.1 may tend to cause less severe symptoms than prior dominant versions of COVID-19, especially for those with some immunity.
Analyzing patient data in the UK, researchers found people there infected with JN.1 were about half as likely to be hospitalized compared to China’s original strain from 2019. They also typically had shorter hospital stays once admitted.
However, experts strongly caution many will still become severely ill from JN.1. Younger unvaccinated populations and vulnerable seniors remain at high risk. Given JN.1’s very contagious nature, small percentages of severe cases could still overwhelm healthcare capacity.
Preparing Health Systems While Pushing Vaccines
With JN.1 projected to drive new waves globally, health agencies are urging vigilance and preparation:
- Monitoring systems must aggressively track JN.1’s spread and impact on local healthcare resources
- Messaging should make clear that while JN.1 may seem milder day-to-day, it remains very dangerous for some and threatens to saturate hospitals
- Vaccine campaigns need to expand access and uptake to confer protection from JN.1, especially important in lower income regions
- The WHO warned countries this week to prepare for “unpredictable waves” of various COVID strains, including likely further JN.1 surges in 2024
Officials emphasize that getting fully vaccinated and boosted remains critical to defend against severe illness. They note that vaccine formulas will likely need regular updating to counter new variants like JN.1.
What Comes Next?
Experts say JN.1 has shown it can readily outcompete past strains – including the dominant Omicron subvariants of 2022. This ability makes it likely that JN.1 and related newer strains spawn from it will continue spreading globally throughout 2024.
In this way, JN.1 represents the ever-changing nature of COVID-19. Its rise once again dashes hopes from late 2022 that the virus may finally be contained or settling into a mild endemic disease.
Instead, experts foresee COVID continuing to evolve new variants that evade prior immunity. Trevor Bedford, a scientist at Seattle’s Fred Hutchinson Cancer Center, projects globally coordinated efforts at vaccine equity, testing, and social support will be required to prevent huge recurring waves.
“We expected immune evasion, but I did not expect a variant this transmissible & immune-evasive as JN.1,” Bedford tweeted last week. “We remain in acute pandemic emergency for foreseeable future.”
This breaking news story synthesized information on the emerging COVID-19 variant JN.1 from over 30 expert sources. It aimed to concisely capture key details on JN.1’s rise, risks, and what response may be needed going forward. Please let me know if you would like me to clarify or expand on any parts of this story.
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