Australia is well prepared should a new COVID variant, which has experts alarmed, arrive in Australia, federal Health Minister Greg Hunt says.

South African scientists have detected a worrying new variant in the country.

So far only about 50 cases of the strain have been detected. But it is particularly worrying for scientists because it has double the number of mutations of the Delta variant, making them believe it might be less vulnerable to immunity from vaccinations.

Britain and Israel have already banned flights from six African nations, including South Africa and Botswana, as more cases of the fast-spreading variant are detected. They are yet to detect any cases of the variant, although it has been found in at least one Hong Kong case.

Only one flight has arrived in Australia from South Africa in the past week. It was a repatriation flight, and passengers are in quarantine at the Howard Springs facility in the Northern Territory.

Mr Hunt – who has met chief medical officer Paul Kelly and health department secretary Brendan Murphy to discuss the emerging strain –said there would be no changes to flights from South Africa.

Nor would the variant prompt any immediate change to the national reopening plan, Mr Hunt said. But, should advice change, the response would be swift.

“We’ve always been flexible, and if the medical advice is that we need to change, we won’t hesitate,” he said in Sydney on Friday.

Mr Hunt said Australia’s high vaccination levels meant the nation was in a much better position to handle new COVID variants than when Delta emerged earlier this year.

More than 86 per cent of the national population over 16 is fully vaccinated and 92.1 per cent have had a first dose.

“The advice remains that the broad-spectrum nature of the vaccines is likely to cover emerging variants, and that’s been the case with Delta and that’s been the case with other variants that have emerged,” Mr Hunt said.

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The WHO was to meet meet on Friday to discuss what the variant – which will be dubbed Nu – might meant for vaccines and treatments, officials said.

“We don’t know very much about this yet. What we do know is that this variant has a large number of mutations. And the concern is that when you have so many mutations, it can have an impact on how the virus behaves,” Dr Maria Van Kerkhove, WHO’s technical lead on Covid-19, said.

In Adelaide on Friday, Prime Minister Scott Morrison said while many COVID-19 variants had been detected, the situation was being watched closely.

“We monitor all of these variants, we note the responses that are made by other countries and we consider those in real time,” he said.

It comes as letters will be mailed to every Australian household before Christmas urging people to get their COVID-19 booster shot.

More than 370,000 people have received their booster shot since they were approved by the medical regulator, but more than 500,000 have been eligible.

However, Mr Hunt said the booster program was ahead of schedule and exceeding expectations.

“Australians do trust the vaccination program. Yes, there’s been the noise of a fringe, but they’re losing the battle,” he said.

“The vaccinators are winning the battle, and I am very hopeful that this early high level of booster acceptance will continue right through the program.”

On Friday, there were 1362 COVID-19 cases in Victoria, with seven deaths reported. It was Victoria’s highest daily case tally in since early November.

NSW had 261 infections, with no fatalities – its second day without further deaths.

One new case was reported in the Northern Territory on Thursday, after the Top End experienced a recent spike in infections. The ACT had eight cases.

-with AAP