The is driving cases in Australia and other parts of the world, but we don't have a vaccine that targets it.
That could soon change though, with global health authorities recommending that vaccine manufacturers update their formulas to target it.
But when could we see new vaccines arrive in Australia?
Current vaccines are not 'optimal'
On Tuesday, the World Health Organization (WHO) and European Medicines Agency (EMA) recommended an update to to target the JN.1 variant.
Professor Raina MacIntyre was part of the WHO team which made its recommendation.
"The JN.1 and variants are the dominant variants in circulation, so the XBB vaccine is not as well-matched. It will still provide protection, but [the new vaccine] will provide better protection," she said.
Clinical microbiologist Dr Paul Griffin also endorsed the calls for an improved COVID-19 vaccine.
"The virus is changing rapidly, immune evasions are on the rise, we have updated the vaccine three times now to keep up to date," he said.
"We need to be agile and adapt quickly."
Health authorities have recommended the COVID-19 vaccine be updated to target the JN.1 variant. Source: AAP / Peter Byrne/PA/Alamy
"The current vaccine isn't optimal with new strains popping up," he said.
"New subvariants like KP2 in the United States are derivatives of the JN.1 strain, so a vaccine targeting JN.1 would be more effective against the new subvariants popping up."
While there is widespread support for a new vaccine, it could take months to arrive in Australia.
Quick to manufacture, slow to approve
Vaccines using mRNA technology can be updated and manufactured in under two months according to MacIntyre and Griffin, but regulatory bodies need to provide the green light, which can lead to delays.
"The speed of the process, from [Australian Technical Advisory Group on Immunisation] recommending it, to [Therapeutic Goods Administration] approvals to roll out is one challenge, which adds to the delay in getting vaccines into arms," MacIntyre said.
A similar approval process is also in place for the flu shot which is updated regularly.
The Therapeutic Goods Administration oversees the licensing of Australian manufacturers as well as verifying overseas manufacturers' compliance with the same standards as their Australian counterparts. Source: AAP
"Australia is pretty conservative in terms of approving quickly, we can be weeks or even months behind other countries like the United States," he said.
"Every year new flu vaccines are approved very efficiently in Australia, but that's not the case with COVID-19 processes."
The US Food and Drug Administration (FDA) Vaccines and Related Biological Products Advisory Committee will meet on 16 May to discuss strain-selection recommendations for upcoming COVID-19 vaccines.
Esterman predicted the US would likely roll out a new vaccine a few months before Australia.
In 2023, the FDA recommended in June that vaccine manufacturers develop a monovalent vaccine targeting the XBB.1.5 subvariant. The first vaccines were rolled out in September.
Winter is coming
The winter months have historically seen a spike in COVID-19 cases in Australia, so there will likely be an increase in the coming weeks.
Esterman said JN.1 could be reported at higher rates.
"We can expect a COVID-19 wave this winter but it will likely be milder than last year," he said.
"In winter people tend to stay indoors more and be closer to others, and given people are more likely to go to hospitals for the flu or sickness, the number of reported COVID-19 positive people will also increase."
SBS News contacted Australia's Therapeutic Goods Administration for comment.
