New coronavirus variants are forcing Australia and New Zealand to rethink already-stringent quarantine rules for overseas visitors, even as their systems are replicated around the world.
Officials in Australia's Victoria state on Wednesday became the latest to warn that the spread of the UK, Brazilian and South African mutations mean its 14-day mandatory quarantine must be toughened.
"These hyper infectious strains are proving very difficult to contain," Victoria state premier Dan Andrews said, signalling coming reforms and announcing the snap closure of a Melbourne quarantine hotel at the centre of a new leak into the community.
"We all have to acknowledge that quarantine and the public health response today must be, by necessity, different than it was a month ago, six months ago," he said.
Health authorities in both Australia and New Zealand this week launched full reviews of quarantine facilities and procedures.
Proposals range from developing outback quarantine centres to testing arrivals more often and for longer.
Since the beginning of the pandemic, around 320,000 travellers have been scooped up at Australian and New Zealand ports and airports, shuttled to quarantine hotels and confined to their rooms for 14 days.
The systems have contained thousands of cases, helping both countries remain largely free of Covid-19.
Places around the world -- including Britain, Canada and Thailand -- are trying to replicate the relative success of such systems, leading Australia's health minister to boast the country's quarantine is the "gold standard" internationally.
But in both Australia and New Zealand there is growing concern about the durability of the protocol.
- 'Time to move' -
As infections worldwide topped 100 million, the number of people arriving with the virus has increased.
On Wednesday alone, New Zealand reported it had detected the virus in travellers from Germany, Tanzania and the United Arab Emirates.
Authorities are also seeing more people arriving with traces of old infections, making it more difficult to sort those with active infections from others.
But the most acute emerging problem is the rise of visitors with more virulent strains -- reaching 105 already in Australia -- with some infections spreading to hotel workers, transport staff and other quarantined travellers.
Several times in recent months the virus has jumped from hotels to the community -- forcing millions of residents in Auckland, Brisbane, Melbourne and Perth into snap lockdowns.
In Victoria, almost 1,000 staff from three outbreak hotels are currently in quarantine themselves.
Few are suggesting completely closing the borders -- particularly as around 40,000 Australians are still unable to return home thanks to strict caps on daily arrivals.
But measures that have already been introduced -- barring hotel quarantine workers from having second jobs, replacing carpet with vinyl flooring, staggering mealtimes and leaving gaps between rooms -- are unlikely to make facilities leakproof.
"It's well and truly time to move quarantine to remote locations, to reduce the risk of transmission into dense urban areas," said Adrian Esterman, an expert in biostatistics and epidemiology at the University of South Australia.
Australia has already identified three remote locations that could be adapted to handle quarantine arrivals -- including an air force base and an offshore immigration detention centre.
Prime Minister Scott Morrison -- with one eye on an upcoming reelection campaign -- has been keen to take credit for the country's coronavirus response.
But quarantine, like much of Australia's measures to control the virus -- aggressive lockdowns, blanket testing and social distancing rules -- has been introduced and run by state authorities.
So far, Canberra has been reluctant to take the reins.
Chief medical officer Paul Kelly warned on Tuesday that placing facilities in remote locations under federal control was not without risk.
"One of the most risky times of transmission during... hotel quarantine is actually the transport from the airport to the actual facility. And so, the longer that is, the more risk there is."
He added that there are "all sorts of reasons why you actually need good care on-site" that might not be available in remote areas.
During quarantine "we've seen mental health issues, we've seen severe other physical issues like end-stage cancer, people about to give birth".
He defended the system as it stands.
"This is really a very good system that has had some issues recently, which we're addressing," he said.
"Can it be improved? Of course, all systems can be continuously improved."