Just weeks after the virus jumped hotel containment lines in Queensland and Western Australia, Victoria now finds itself in the hot seat.

The latest cluster of more than a dozen cases is believed to have spread through the use of a nebuliser at the Holiday Inn near Melbourne Airport.

“You can test everybody every day … but it’s a different challenge now, it’s not the 2020 challenge, it’s a very different virus,” Premier Daniel Andrews told the media on Friday, as the state was plunged into a five-day snap lockdown.

With the emergence of international variants of the virus throwing a new spanner in the works, questions are again being raised about some of the weaknesses of Australia’s quarantine programs, and how our lines of defence might be strengthened.

So how are other countries managing the crisis? And is there anything we can learn from their quarantine systems?

New Zealand: Hotel quarantine

Australia is not the only country using hotels to quarantine overseas arrivals — nor is it alone in experiencing major problems with its approach.

New Zealand, which last month recorded a cluster linked to the Pullman Hotel in Auckland, implemented a Managed Isolation and Quarantine (MIQ) system in the early months of the pandemic.

Under that system, returning travellers must apply for a “voucher” securing their place in hotel quarantine for at least 14 days before they are able to board their flight home.

New Zealand implemented a Managed Isolation and Quarantine (MIQ) system in the early months of the pandemic.(AP: Nick Perry)

Those travelling from all destinations except Australia, Antarctica and some Pacific islands must submit to a COVID-19 test within 24 hours of their arrival, with follow-up testing on days three and 12 of quarantine (prior to January 18, this order only applied to travellers from the United States and United Kingdom).

“What is common to all systems … is that we are constantly learning from the mistakes we are making, and constantly … getting smarter and sharpening up things and finding finding leaks,” said Victoria University professor and public health expert, Maximilian de Courten.

According to Professor de Courten, no system is infallible, and trying to make quarantine facilities “99 per cent watertight” risks either reducing the intake capacity for returned travellers, or “causing a lot of psychological impacts”.

Rather, he says, authorities are placing a greater focus on strengthening the defences supporting those quarantine systems: “Let’s not only look at what happens and what we can do and should do in the hotel, but the rings around that system,” he said.

Last month, for example, in response to concerns about “high rates of infection and new variants of the virus and their potential to spread more rapidly”, New Zealand introduced mandatory pre-departure testing for travellers from the UK and US, before extending it to all but a handful of countries just 10 days later.

“Contact tracing, testing quarantine staff … it is incredibly important to make sure that we don’t have an outbreak of a virus, but rather a controlled breakout,” Professor de Courten said.

In response to the Holiday Inn outbreak, Mr Andrews said he would have “more to say about the future of hotel quarantine very soon”, signalling changes to the intake of international arrivals may be imminent.

Singapore: Electronic tracking

Like Australia and New Zealand, Singapore also introduced 14 days of mandatory hotel quarantine last year.

But after flattening the curve, those restrictions were eased in August, allowing travellers from low-risk countries to undertake just seven days of self-isolation at home, alongside a COVID-19 test at their own cost.

The catch, however, is that all travellers over the age of 12 who are not staying in a quarantine facility must wear an electronic tracking wristband, issued to them after clearing immigration.

International arrivals are required to activate it upon reaching their place of residence, and authorities are alerted if they attempt to leave or if they tamper with the device.

Of the 308,442 stay-home notices issued up until January 25, 367 breaches were recorded, Singapore authorities said.

In Hong Kong and Abu Dhabi, international arrivals are similarly required to wear a wristband while self-isolating for two weeks.

European Union: ‘Traffic light’ system

In a bid to develop a “coordinated approach to travel restrictions in the context of COVID-19”, European Union countries adopted a common “traffic light” system in October, guiding them on testing and quarantine during the pandemic.

Regions across the union are assigned a green, orange, red or dark red (to take into account new variants) label, based on the degree to which the virus is under control.

“In Europe, there is far more travel between borders and land borders, which are far more difficult to control, and establish a hotel quarantine system like we have here, where we only have a limited number of airports,” Professor de Courten said.

“So in other countries, their incoming infection quarantine system is basically not really effective at all.”

While individual EU countries are free to determine their own measures, they are encouraged to be consistent by setting the same measures for all red zones.

In Finland, for example, travellers must have proof of a negative COVID-19 test, taken in the 72 hours prior to arrival. They must then quarantine for 72 hours until a second negative test is returned.

The Netherlands similarly requires travellers from “red” countries to present proof of a negative PCR test, taken 72 hours before departure.

Unless exempt, international arrivals must self-isolate for 10 days — although those who arrange to get tested on day five may be eligible to shorten their quarantine period.

Individual EU countries are free to determine their own measures.(Reuters: Guglielmo Mangiapane)

“We’ve been able to act very quickly and keep the [coronavirus case] numbers really low, so it’s much easier and more effective to trace and monitor for a handful of cases than [thousands],” said Professor de Courten. “So one has to have that in mind when judging the effectiveness of quarantine systems.

“It’s a little bit unfair to compare a country sitting in the middle of Europe with Australia or New Zealand.”

United States: Blocking flights

In the United States, returning travellers must be able to show proof of a negative COVID-19 test before they are able to fly and, upon arrival, are required to undertake a viral test within 3—5 days, and self-quarantine for one week.

But in a bid to slow the spread of the virus, the nation has gone a step further, banning travellers from China, the United Kingdom, Brazil and South Africa (among others) from entering.

“If you spot a source, where there’s an infectious outbreak, do you try to cut the transmission line — the influx from that source — once they’re here to quarantine? Or ban people coming from there?” Professor de Courten said.

In the United States, returning travellers must be able to show proof of a negative COVID-19 test before they are able to fly.(AP via David Joles/Star Tribune)

“However, it has many implications. And at the moment [with the virus] being a global problem … you might have to ban half of the world or even more from coming to Australia.”

In response to concerns about new variants of the virus, the United Kingdom last month announced a travel ban on 33 “red list” countries, including South Africa and parts of South America.

From February 15, travellers arriving from hot spots will be permitted entry, provided they undertake 10 days of hotel quarantine.

So what can we learn from all of this?

Adrian Esterman, a professor of biostatistics and epidemiology at the University of South Australia, says Australia has fared much better than many pockets of the world, but argues that “the real problem now is these new, highly contagious variants”.

If the virus escapes hotel quarantine, the risk of it spreading through cities is simply too high, he says.

“There’s absolutely no reason why we couldn’t put out quarantine stations in rural or remote areas, is all doable,” Professor Esterman said.

“It does cost money. But then the cost of lockdowns totally outweighs the cost of setting up quarantine stations in remote areas.”

Some are advocating for mandatory quarantine to be moved to regional or remote areas.(AAP: Jeremy Piper)

Professor de Courten believes Australia could “design and use a much more watertight system” for quarantining overseas arrivals.

“But that’s not suitable for what we also want to achieve, which is bringing in a lot of people,” he said.

Pointing to strengthened “ring fences” around the hotel quarantine system (like testing and tracing), Professor de Courten says the national vaccine rollout could be a “gamechanger”.

“For instance, if we would contemplate to vaccinate as a first line, point of contact, all the airport staff, the hotel staff, security staff, and so on … that would be another ring, making it less likely that a virus could break out in the community,” he said.

We could also require people entering Australia from overseas to have been vaccinated, he said: “And that would also reduce very much the influx of the virus and make the rest of the quarantine system work better.”