Many governments have decided to isolate arrivals because of coronavirus despite little agreement about how to go about it.
When Hope Ailsa checked in to the luxurious InterContinental Sydney hotel for 14 days of coronavirus quarantine, she soon found she was not about to have anything resembling a holiday.
"We weren't allowed outside our room," says the superyacht captain, who returned home from the Philippines in April after Australia brought in some of the earliest and tightest pandemic quarantine rules.
"The windows didn't open and there was no fresh air. They posted two guards on each floor and if you opened your door they would stare at you and tell you to close it."
"I was crying," she says, explaining she is a heavy smoker and had savage withdrawal symptoms until the reception desk ordered nicotine patches. To get through her stay she started running laps of her room, covering about 1km a day, and took up toilet-roll bowling.
• Covid 19 coronavirus: Health officials with today's case number update as Cabinet considers level 1 date
• Covid 19 coronavirus: What are New Zealand's rules at alert level 1?
• Covid 19 coronavirus: The big Kiwi company hanging on to pandemic refunds
• The Covid-19 business change that was so successful, they had to hire more staff
Her experience convinced her that two weeks in captivity, even in a five-star hotel overlooking the Opera House, could affect mental health. Yet she still thinks that confining apparently healthy people is necessary. Being free to travel and spread infection would be unfair, she says.
Her support for a practice that dates back to at least the Middle Ages is widely shared. More than 140 countries and territories have brought in quarantine measures since January, according to data compiled by the International SOS medical and security services group, a level experts say is unprecedented.
With little obvious debate and consultation, or even agreement among scientists about when to apply it, governments around the world have decided that isolating arrivals from other countries is an essential response to coronavirus — and, in some cases, could remain so for quite some time.
"We are witnessing a unique moment in history," says Eugenia Tognotti, professor of history of medicine at Italy's University of Sassari. "There has never been another time when such a large percentage of the global population has faced quarantine."
For some public health experts, the speed at which countries have cracked down on people's movement to stem the spread of the virus has come as a relief.
"I was very happily surprised," says Dr Rodrigo Rodriguez-Fernandez, a medical director at International SOS. It is hard enough to put a national healthcare policy in place, he says, so the rapid spread of quarantine measures was "really refreshing".
Yet this new world of confinement has also brought problems. Human rights groups say some governments have used quarantine as a pretext to make arbitrary arrests or boost military action.
Elsewhere, rules have sprung up so haphazardly it has created a confusing hodgepodge of travel rules that have begun to alarm transport and tourism companies.
Authorities have commonly quarantined arriving travellers for 14 days, a period researchers deemed safe for a virus with an average incubation period of about five days. But the rules are by no means uniform.
Quarantine in Myanmar has meant up to 21 days of confinement for some arrivals. Samoa has required 14 days of isolation before you arrive and 14 days after you get there. Some countries put you in a hotel; others let you go home. Some require a test for Covid-19 before arrival, others once you get there.
For the travel and tourism industry, which supports an estimated one in 10 jobs worldwide, this jumble of measures is a worrying reminder of what happened after the September 11, 2001 attacks in the US, when countries launched an array of different airport safety rules, many of which lasted until this year.
That lack of alignment after 9/11 is one reason it took the industry five years to recover, says Gloria Guevara Manzo, chief executive of the World Travel & Tourism Council. "We have to learn from the past," she told a Financial Times conference last month, adding it took only 18 months for the sector to regain its feet after the 2008 financial crisis when there was better co-ordination among countries.
However, more than four months after the first coronavirus quarantine measures were imposed in China, where the outbreak began, co-ordination has been slow internationally and even within individual countries. In the US, Texas began easing its 14-day quarantine rules for out-of-state visitors as early as April but similar restrictions were still in place last week in states such as Alaska.
The disparity is especially acute in Europe, where countries including Italy, Spain and Greece are planning to loosen their quarantine requirements as summer nears — just as the UK, one of the region's largest economies, introduces them.
The UK has bucked international trends throughout the pandemic by failing to impose the quarantine rules, airport testing or tighter border controls that other nations introduced. To the fury of British airlines and hotels, it has now decided that from June 8, arrivals from abroad will have to self-isolate for 14 days or face a £1,000 ($2,000) fine.
There will be exemptions for freight drivers, doctors and others. But the step is "the very last thing the travel industry needs", according to a letter to the government endorsed by more than 200 travel and hospitality companies. The "unworkable" move would deter foreign visitors and probably spur reciprocal quarantine requirements on British travellers, they said.
Boris Johnson, the prime minister, has said the government did not bring in quarantine earlier because "the scientific advice was very clear that it would make no difference" to the arrival of the epidemic. It was acting now, as infection rates were falling, because it did not want to see a wave of reinfection from abroad, he said.
One scientist who has attended the UK government's scientific advisory group on emergencies, or Sage, told the FT in April that quarantine would have been economically disastrous for an island nation supplied by thousands of Channel-crossing lorries each day.
This is not the first time Britain has stood out on such matters.
The World Health Organisation was created in 1948 in the wake of a series of 19th-century "international sanitary conferences". These wrestled with the need to agree on quarantine procedures to stop the spread of diseases, such as cholera, without unduly disrupting international trade.
At the first conference, convened by France in 1851, "maritime nations, notably Britain, wanted to minimise any health regulations that would interfere with the free flow of trade", says a paper by Charles Clift, senior consulting fellow at the Chatham House think-tank who has studied the history of global health institutions.
The editor of a German medical journal later noted the "surprising concordance between England's commercial interests and its scientific convictions", the paper adds.
The struggle to preserve both public and financial health has continued ever since, not least when it comes to the current pandemic.
The World Health Organisation has long been wary of curbing the movement of people or goods in a public health emergency, in part because it says such restrictions are often ineffective and can have negative economic effects.
Asked last week if this was still the case, a spokesman pointed to written WHO advice saying travel measures that significantly interfere with international traffic for more than 24 hours "may have a public health rationale at the beginning of the containment phase of an outbreak", as they can buy time for countries to prepare.
"Such restrictions, however, need to be short in duration, proportionate to the public health risks, and be reconsidered regularly as the situation evolves," it said.
So why have so many countries ignored this? One possible answer: panic. Covid-19 spread at a much faster rate than most countries expected. The sight of overwhelmed hospitals in developed countries such as Italy may have jolted governments into action.
In many countries, the public welcomed the move. Quarantine has been part of a suite of travel restrictions credited with keeping death rates low in countries such as New Zealand and Australia, which had recorded fewer than 130 Covid-19 deaths between them at the time of writing.
At one point, more than two-thirds of Australia's confirmed Covid-19 cases were returning travellers, according to Brendan Murphy, the country's chief medical officer. More than 33,800 people have been quarantined in the country since both national and internal state borders began to close in March, mostly in hotels with governments footing the bill.
Things have not always run smoothly. In Perth, a man was jailed after repeatedly sneaking out of his quarantine hotel room. A 70-year-old man in the same city ended up in intensive care after falling ill in hotel quarantine where his wife's pleas for medical help at first went unanswered.
In New Zealand, anguished relatives have gone to court to overturn quarantine rules that stopped them seeing dying family members.
But the countries' success in stemming the virus shows that measures such as quarantine work, says Dr Bharat Pankhania, senior clinical lecturer at the University of Exeter's college of medicine and health.
"It worked. What more do you want?" he told the FT. The UK's larger population and arrival numbers might have made quarantine harder but not impossible, he added. "Because that was seen as a tall order, they said, 'can't be done'. Anything is possible if you want to do it."
An era of travel bubbles?
Some countries have begun to ease their quarantine measures, but for financially stricken airlines the policy has been a source of contention from the start of the pandemic.
"We are concerned about the deployment of such measures of quarantine because it is a major deterrent to air travel," says Alexandre de Juniac, director-general of the International Air Transport Association.
Instead of quarantine, aviation and tourism companies are pushing for common international standards on how to manage travel, including temperature checks at airports, wearing face masks during transit, social distancing where possible at the airport and increased cleaning of equipment.
The travel industry is also backing quarantine-free "air bridges", "bubbles" or "travel corridors" set up between countries with low infection rates. Australia and New Zealand have agreed to establish a "Trans-Tasman travel bubble", while countries including Israel, Greece and Cyprus have discussed a tourism safe zone in the eastern Mediterranean.
John Holland-Kaye, chief executive of London's Heathrow airport, where average passenger numbers have fallen from about 250,000 a day to almost 6,000, says there are other factors to consider.
"There is no perfect way currently to say that one person has the disease and another one doesn't, but we can say one country is low-risk and, therefore, we should accept passengers coming in from there. And, reciprocally, they will accept passengers from us if we are seen as low risk," he told the FT.
"It seems exactly the right kind of approach rather than a blanket 14-day quarantine to any arriving passenger which will stop people flying and hold back the economy," he said.
Heathrow is working with 10 other major hub airports around the world, including Hong Kong, Sydney and San Francisco, to try to establish the same health measures globally, as a way of fast tracking the "air bridge" idea. However, this is ultimately a decision for governments.
Meanwhile, anyone hoping to see an end to quarantine soon cannot ignore the country where the coronavirus outbreak began: China.
It is now more than four months since Wuhan, the city where the virus was first detected, was cordoned off. Mass quarantine later enveloped the entire province of Hubei and its 60m people. Measures were later adopted to safeguard Beijing from exposure to the virus, keeping the capital's total number of infections to about 500.
While foreign arrivals to China have drawn to a trickle, internal travellers have been subject to strict but inconsistent quarantine rules.
When Wuhan reopened to travel on April 8, those heading to Beijing found the trip more difficult than advertised. Arrivals were greeted by local officials in hazmat suits who bussed them directly from the train station to their home or government facility.
Some districts allowed returnees to quarantine at home with relatively few restrictions; in some cases a note promising not to set foot outside sufficed. In other districts, officials taped shut the returnees' doors and put a sensor device outside the door that would alert authorities if it was opened.
Some areas of Beijing refused all residents returning from Wuhan, barred them from going to their homes and forced them to proceed directly to a government facility for a 14-day stint.
How quarantine rules differ across the world
• United Kingdom: From June 8, residents and visitors will be required to spend 14 days self-isolating in one place, or face a £1,000 fine. People will also be asked to provide contact details and may be fined £100 if they refuse.
• Hong Kong: On arrival, passengers without symptoms must be tested for Covid-19 and then await the results. People with negative results may be able to leave and go home for 14 days of compulsory quarantine, during which they must check their temperature twice daily and record their health conditions.
• Austria: Non-citizens coming in by land from neighbouring countries must present a health certificate no more than four days old that confirms a negative test result for the virus. Citizens returning home must undergo a 14-day home quarantine and if a test done during this time is negative, the quarantine can be ended.
• Indonesia: Arrivals must show a health certificate confirming a negative Covid-19 result from a test taken no more than seven days before arrival. Those who arrive without such a certificate are required to undergo a test and quarantine on arrival, at their own expense, until the test results are received, which can take up to seven days.
• Ireland: Arrivals from abroad, including returning Irish citizens, must stay indoors and avoid contact with other people for 14 days.
Written by: Pilita Clark, Tanya Powley, Jamie Smyth and Don Weinland
© Financial Times