What is the Omicron JN.1 variant?

JN.1 first emerged from the Omicron variant BA.2.86, unofficially dubbed “Pirola”.

Pirola has more than 30 mutations on its spike protein compared to the BA.2 Omicron variant that emerged in early 2022. Pirola raised alarms when it emerged because it was so heavily mutated, sparking fears it could take off as a highly infectious, vaccine-resistant strain.

“After the initial waves of the original Wuhan strain, and then the Alpha, Beta, Delta waves, the next big change was Omicron, which was over 30 mutations away from Delta,” says Adrian Esterman, a professor of biostatistics at the University of South Australia.

He says the emergence of Omicron was followed by subvariant after subvariant, until we hit BA.2.86, or Pirola, which was again more than 30 mutations away from any previous subvariant – just as the original Omicron had been. “It’s been a major, major shift,” he says.

JN.1 has an additional mutation on its spike protein that makes it very transmissible and better at evading the immune system, which is why it’s fast becoming the dominant strain in many countries, including France, Canada, the US and India.

“It was initially thought that BA.2.86, or Pirola, would really take off around the world, and it didn’t. With this new mutation, it now has,” says Esterman

Omicron, Delta … is JN.1 our Pi?

The World Health Organisation dubbed JN.1 a variant of interest in December. Variants earn a name from the Greek alphabet only if WHO regards the strain as significantly more infectious or severe than previous iterations of the virus.

Some experts have argued BA.2.86 and JN.1 have proved sufficiently infectious to warrant the next letter in line – Pi. That’s also part of the reason BA.2.86 was unofficially dubbed Pirola; the name comes from a combination of Pi and Rho, the next Greek letters in line after Omicron.

“It is more transmissible, but whether it’s so much more transmissible that it would warrant its own name is another issue,” Esterman says. “But also, there is no evidence at the moment that it causes more severe disease.”

Studies published this week in scientific journal Cell used an artificial form of the BA.2.86 strain – called a pseudovirus – built by scientists in a lab. The study found the virus entered lungs more efficiently compared with previous Omicron strains, which the researchers wrote was more characteristic of early, more severe iterations of COVID that infected the lower respiratory system and the lungs rather than milder infections in the upper respiratory tract.

But Esterman says there was a better laboratory that showed JN.1 wasn’t actually causing significantly more severe disease: America.

“In the USA, you’ve got 64 per cent of all cases being JN.1. We’re not seeing a major increase in hospitalisation. We’re really comparing test tube research to what’s happening in real life.”

How should we respond to the new variant?

Even though it seems JN.1 isn’t significantly nastier than its predecessors, every COVID-19 infection brings the risk of severe illness and of debilitating long COVID. The chance of contracting long COVID varies widely depending on who you are and what strain you catch, but Australia’s parliamentary inquiry into long COVID found the risk is between 2 and 20 per cent.

Recent Australian research, yet to be peer-reviewed, found 18.2 per cent of triple-vaccinated COVID patients had long COVID symptoms 90 days after infection.

JN.1’s extra spike mutation makes it more immune evasive, meaning antibodies find it tricky to pin down and kill. But the good news is that the most recent vaccine to become available in Australia, the monovalent XBB.1.5 vaccine, works well against BA.2.86 and JN.1, according to the latest research.

NSW Health’s McAnulty is urging people to meet outdoors, stay at home if experiencing flu-like symptoms, and get boosted. Esterman says he expects to see more hospital beds taken up by COVID patients in coming weeks.

“We should be really encouraging people at risk to get their booster shots, and to protect themselves with face masks when they’re going out.”

With the end of robust testing data, it’s impossible to know exactly how many people are infected. But based on wastewater analysis, antiviral prescriptions and hospitalisations, Esterman estimates that we’re in for a significant wave.

“My own guess is that we’ve got a fairly massive outbreak at the moment.”

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