The World Health Organisation says it is keeping a close eye on a new form of the Covid-19 Delta variant as cases soar across several European countries.
While it is not the driving force behind the UK's rise in Covid cases in recent weeks, the new form, named AY.4.2, has triggered an outbreak in Britain.
It has also been detected in Russia, Germany, Denmark and the US.
While it is unclear at this stage whether the variant is more contagious than the original Delta variant, there is caution over its emergence.
It comes as Australia presses ahead with reopening its international borders, ddespite concerns having been raised at the eagerness to do so.
NSW Chief Health Officer Dr Kerry Chant previously warned of the dangers of opening up and co-existing with the virus, stressing future "curve balls" were likely.
"God help us if we have another variant," she said in August.
Modelling published in the Medical Journal of Australia from the Centre for Big Data Research in Health at UNSW found the nation's healthcare system could be overwhelmed if a new variant as infectious as Delta emerged with pre-pandemic levels of international travel.
“The planned reopening of Australian borders to international travellers increases the risk of introducing new chains of infection and new variants of SARS-CoV-2,” the modelling found.
“Political and health system policymakers should not focus exclusively on defining vaccination thresholds at which particular restrictions might be removed. Instead, they should recognise that mass vaccination is unlikely to achieve complete protection against Covid-19.”
The impact of new Delta variant AY.4.2
Oxford Vaccine Group chief Andrew Pollard told the BBC the AY.4.2 variant is "unlikely to change the picture dramatically" in largely vaccinated populations.
But AY.4.2 cases are rising in the UK, with close to 10 per cent of daily cases now the new variant.
It comes as the UK battles a surge in cases with reported daily infections just shy of 50,000.
Deaths have risen by 21 per cent in the past week, with 223 on Tuesday – the highest since March.
It has prompted increasing calls for restrictions to be reintroduced in the UK in a bid to prevent the health system being once again overwhelmed.
There are fears cases will balloon further heading into winter, with up to 100,000 a day feared.
Cases are also surging in France and Latvia, however vaccination rates in the latter are lagging.
The variant has yet to be detected in Australia and Chief Medical Officer Professor Paul Kelly downplayed its severity but did say there's "close vigilance" for any further developments or variants which could cause issues for Australia.
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