TRANSCRIPT
Almost four years into the COVID-19 pandemic, the JN.1 variant is driving a surge of infections around the world - and in parts of Australia.
Classified as a variant of interest by the World Health Organisation last December, it's now responsible for 64% of coronavirus cases in the United States.
It emerged from an Omicron sub-variant known as BA.2.86.
University of South Australia epidemiologist Professor Adrian Esterman says a change in the spike protein of virus - the area where the virus sticks to cells - makes it more transmissible.
"It's allowing JN.1 to better evade our immune system. So even if you've recently had COVID-19 or been vaccinated, it has made it much easier for JN.1 to infect you. This is why we're seeing it now starting to dominate around the world."
That transmissibility is now being seen in Australia.
The JN.1 sub-variant now makes up more than a third of COVID cases in New South Wales and is the most prevalent sub-variant in wastewater samples in Victoria.
Both states have seen a recent spike in COVID cases and hospitalisations.
Around 400 people were admitted to hospital in New South Wales, and 377 in Victoria, in the latest seven-day reporting period.
Queensland has seen a prolonged surge in cases since last October.
So, should Australians be worried about a new JN.1 wave?
Professor Esterman says, although more transmissible, the sub-variant was thought to attack the upper respiratory systems, and not the lungs - making it less severe than other variants, such as Delta.
That is, until a few days ago.
"But a couple of recent studies, only in the last few days have shown that JN.1 does actually like to attack the lungs. Now, you might think, oh, no, it's Delta again. But they're not actually seeing a major increase in hospitalisations. So, the real-world data shows that it doesn't appear to be more severe, but some lab data shows it could be."
Virologist Stuart Turville, from the University of New South Wales' Kirby Institute, says the new variant needs to be monitored closely.
"We've got to be mindful that there's a lot of things we don't know about the virus. And this has changed in a manner where it is replicating in the lab, we're seeing it replicated in the lab very, very differently for many other variants that we've seen before."
Professor Esterman says vaccines released from December are much better at providing immunity to the JN.1 and XBB.1.5 subvariants, than those released before then.
And that's a concern because only 22 per cent of those aged 75 years or over have received a COVID-19 booster within the past six months.
For 65-to-74-year-olds, only 15 per cent are up to date.
"These are the highest risk groups. And even worse, is that only about something in the order of 40 per cent of aged care residents update their booster shots. These are our most vulnerable populations. So clearly there's a lot needs to be done to protect vulnerable people."
ATAGI, the Australian government's vaccine advisory body, a recommends a COVID vaccine booster every six months, for those over the age of 65, or at higher risk of severe illness.
For most people under 65, a booster is recommended yearly.
New South Wales Head of Health Protection Dr Jeremy McAnulty last week urged Australians over 65 and with a compromised immune system to update their vaccinations.
“While vaccine can wane over time in terms of getting infected, it still gives you robust protection against getting serious disease and death, so vaccine remains a very important part of our way of controlling COVID."
Virologist Stuart Turville says he is hopeful that immunity among the population will improve over time with the release of more boosters, gradually reducing the impact of COVID-19.
“But what we're seeing now in the population is that maturation, they're better-quality antibodies that are being produced, the more cross reactive, and we're seeing the antibodies even bind to variants that, you know, at the time didn't exist. I'd say that over time, that trajectory will become better and better and better, and hopefully, hopefully, we'll corner the virus.”
