A new COVID-19 subvariant with a high number of mutations has raised alarm among scientists.
The new strain is officially called BA.2.86 but has been nicknamed 'Pirola'.
The new strain detected in Australia has hastened a vaccination program for vulnerable groups and healthcare workers in the United Kingdom.
Kirby Institute associate professor Stuart Turville said this new variant was different from others circulating in the community.
"The reason this is different is that it has probably been in somebody that's chronically infected with the virus.
"So it's an unseen variant that's growing and evolving in somebody," he said.
"Because it's very different to the other ones that are circulating, we don't have a high confidence in what it's up to."
Pirola is a subvariant of the Omicron variant descended from the BA.2 strain that led to widespread COVID-19 cases at the start of 2022.
The World Health Organization labelled BA.2.86 a "variant under monitoring" in its second tier of notable COVID variants.
It has emerged across the globe, including in Denmark, Israel, France, the UK and the US.
The new strain has 34 more mutations than BA.2 and 36 more than XBB.1.5 (dubbed "Kraken" and the strain recommended for vaccination) according to researchers at the Fred Hutchinson Cancer Research Institute.
While little is currently known about the transmissibility of Pirola or whether it will cause severe disease, scientists did not expect it to be much different from previous Omicron strains currently in circulation.
The most recent variant of interest 'Eris' became dominant in the US and accounted for 17.4 per cent of cases worldwide by the end of July.
Associate professor Turville said early studies suggested the new variant was not as proficient as current circulating variants at evading antibodies released from an immune response.
And Moderna found its latest booster vaccine helped protect against Pirola.
Professor Turville said he was most concerned with community apathy around booster shots.
"At the beginning of the pandemic it felt like a marathon, with governments running a sprint.
"Now we're midway through the marathon, we went so fast at the beginning and now it feels like we've stopped," he said.
According to the Department of Health, only 53 percent of people aged 65 years and older have received a booster dose in the past six months.
IN OTHER NEWS:
Over the week to September 12, there were 5,069 cases of COVID-19 reported across Australia, an average of 724 cases per day.