Concerns are mounting over a new variant of COVID-19, dubbed JN.1, which appears to be driving a new wave of infections globally. According to experts, JN.1 is the most transmissible form of COVID yet and its unique mutations allow it to more easily evade existing immunity.
JN.1 now dominant strain in the US
The CDC reports that JN.1 accounts for over 60% of current COVID-19 cases in the US. The new wave of infections, fueled by holiday gatherings, is the largest seen since Omicron emerged over a year ago:
The fast spread of the new JN.1 subvariant has led to the nation’s largest coronavirus wave since last winter’s omicron surge. Hospitalizations are on the rise, too, though deaths haven’t substantially increased so far. Source
JN.1 appears to be markedly more transmissible even than past variants like Omicron and Delta. Its rapid rise over the holidays has alarmed health officials bracing for further spikes as schools reopen and people return to offices.
Dr. Eric Topol of Scripps Research told NBC News:
“It’s as transmissible as any variant we’ve seen,” Topol said. JN.1 is “starting to take over very quickly, similar to what omicron did a year ago.”
Three common early symptoms of JN.1 infection
Experts say JN.1 presents differently than prior variants, with some distinct symptoms:
- Fatigue
- Body aches
- Fever
These tend to manifest first, while respiratory symptoms like coughing and sneezing appear later.
Fatigue has been reported as one of the first signs of someone with the JN1 variant. […] Body aches and pains has also been reported as an early sign of JN1 infection. […] Fever is one of the three most common symptoms first reported in JN1 patients, emerging early on along with fatigue and body aches. Source
This ordering of symptoms contrasts with earlier variants and could complicate detection without testing, as upper respiratory symptoms often triggered clinical suspicion for COVID-19.
JN.1’s enhanced immune evasion drives reinfections
Experts believe JN.1’s constellation of new mutations allows it to circumvent existing immune defenses more successfully than past variants:
JN.1 has an “unprecedented” number of mutations compared to the original COVID-19 virus first detected in Wuhan, with around 10 mutations on the spike protein that the virus uses to enter and infect cells, said Dr. Stuart Ray, a professor of medicine at Johns Hopkins University. This spike protein is the target of leading COVID-19 vaccines.
The mutations allow the subvariant “to escape pre-existing immunity with greater ease than its predecessors,” Ray said. Source
This capacity for immune evasion appears to be driving rising rates of reinfection:
New estimates released by the Office for National Statistics showed that the number of reinfections in England hit a record high in the first week of December, with 10.1% of positive COVID-19 cases likely reinfections. Source
Reinfections with JN.1 progress similarly to or slightly worse than primary infections. Fortunately, vaccination continues to provide substantial protection against severe disease and death even from this new variant.
Global spread prompts renewed precautions
With JN.1 outbreaks now detected across Europe, Asia, and the Americas, many countries are reinstating restrictions and masking recommendations:
| Country | Key Precautions |
|---|---|
| United States | Universal indoor masking in high-risk areas Enhanced availability of boosters |
| United Kingdom | Work from home where possible Masks mandated on public transport |
| India | Masks compulsory in public in major cities “COVID-appropriate behaviour” urged |
However, some experts argue that populations cannot sustain stringent restrictions forever against an evolving virus. Rather, efforts should focus on increasing accessible testing, evaluating further boosters targeted at new variants, ensuring availability of antivirals, and monitoring for dangerous mutations:
“We have to recognize that SARS-CoV-2 is going to circulate pretty widely,” says [Dr. Peter] Chin-Hong [of UC San Francisco]. “But that doesn’t mean that contact precautions, making tests more available, making antivirals more available to vulnerable people so they avoid hospitalization and death — those things will continue to be utterly important.” Source
Only time will tell whether the JN.1 wave crests or proves merely the first swell of a new COVID-19 surge. In the meantime, obtaining updated boosters as available and avoiding unnecessary risks remain our best defenses against both this virus and whatever successor variant may someday replace it.
Addendum: Long-term symptoms still pose puzzles
While acute infections with new variants like JN.1 resemble those from past versions of the virus, the prevalence and duration of so-called “long COVID” symptoms remain less clearly understood:
COVID-19 vaccines dramatically reduce the risk of developing long-term symptoms, according to a survey of more than 1.2 million people published Wednesday in Nature Medicine. However, even vaccinated people have higher rates of long COVID than expected from pre-pandemic control groups. Source
Lingering effects may impact over 25% of infected children:
Long COVID “is not nearly as common as a simple runny nose or a cough. But it’s common enough — over 25% of kids — that all pediatricians not only need to be aware of it but also know what to do about it,” said Dr. John McGuire, division chief of general pediatrics and adolescent medicine at Seattle Children’s Hospital and a member of the American Academy of Pediatrics’ steering committee on COVID-19. Source
Ongoing research aims to shed light on appropriate diagnosis and management of long COVID’s protean symptoms. In the meantime, prevention via vaccination remains critical given these persistent complications’ impact on quality of life.
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