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Covid-19: WHO adds JN.1 as new variant of interest

BMJ 2023; 383 doi: https://doi.org/10.1136/bmj.p2975 (Published 21 December 2023) Cite this as: BMJ 2023;383:p2975
  1. Mun-Keat Looi
  1. The BMJ

The World Health Organization has added a new covid-19 strain, JN.1, to its list of “variants of interest,” its second highest level of monitoring.

Itself an offshoot of the omicron subvariant BA.2.86 (nicknamed “Pirola” by the media),1 JN.1 is described by WHO as posing a “low” risk to global public health. The agency warned, however, that the winter season in the northern hemisphere could increase the burden of respiratory infections in many countries.

Having made up just 3% of infections in early November, JN.1 is now responsible for over 27%, WHO said.2

JN.1 was first detected in 12 countries in September, the highest proportions being in Canada, France, Singapore, Sweden, the UK, and the US. The UK Health Security Agency has told the BBC that JN.1 is found in about 7% of the positive covid-19 tests analysed.3

Data from the US Centers for Disease Control and Prevention (CDC) show that JN.1 is the fastest growing covid strain in the US, responsible for 15-29% of new covid infections.4 It is already the dominant strain in the north east of the US, where it is responsible for a third of all cases.5

T Ryan Gregory, an evolutionary biologist at the University of Guelph in Canada, told CNN, “It’s already pretty clear that it is highly competitive with existing XBB variants and looks like it’s on track to become the next sort of globally dominant group of variants.”

Current vaccines

The US CDC said that there was only a single change between JN.1 and BA.2.86 in the spike protein on the virus’s surface, which helps the virus infect people.6 Since the spike protein is also the part that existing vaccines target, current vaccines should work against JN.1 and BA.2.86.

The CDC said, “Initial scientific data show that the updated 2023-2024 covid-19 vaccines help our immune systems block BA.2.86. We expect JN.1 will be similar. We also expect treatments and testing to remain effective based on analysis conducted by the SARS-CoV-2 Interagency Group (a group of scientific experts representing many government agencies).”

WHO has emphasised that current vaccines continue to protect against severe disease and death from JN.1 and other circulating variants of SARS-CoV-2—the virus that causes covid-19—and has urged people to stay up to date with their vaccinations, particularly those at high risk of disease.

The UN agency also warned that covid-19 was not the only respiratory disease circulating. Flu, respiratory syncytial virus (RSV), and common childhood pneumonia were on the rise, it said, reminding people to wear masks, wash their hands regularly, cover any coughs and sneezes, and stay at home if sick.

Katelyn Jetelina, an epidemiologist, said that JN.1 “has become the fastest growing variant in the past two years,” adding that public wastewater indications showed that the strain was exponentially increasing.7

“The big question is if and how hospitalizations will follow wastewater trends, especially in places like the US, where vaccination rates are low,” she wrote. “The UK and Singapore, which have high vaccination rates, are seeing a steep increase in hospitalizations now that JN.1 has taken over.”

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

Footnotes

  • Katelyn Jetelina was a BMJ editor from 2020 to 2022.

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