SYDNEY (BLOOMBERG) - A global travel divide is deepening as some countries ditch Covid-19 restrictions, including quarantines, isolation and even mandatory testing for good, while others cling to years-old curbs.

Lingering barriers to travel in Asia, in particular, are isolating the region and its tourism-reliant economies, just as the recovery in Europe and the United States accelerates. In Britain, the authorities are dumping unpopular pre-flight tests and now require only proof of vaccination as they strive to normalise international air traffic.

The marquee transit hubs of Hong Kong and Singapore are being shunned as travellers seek to avoid weeks in hotel isolation on arrival or a raft of testing swabs.

Airlines, which before the pandemic operated about 30,000 flights a month to the two Asian gateways, have slashed that number to just 4,514 in February, according to aviation data company Cirium.

There is little prospect of immediate change. Hong Kong - which quarantines overseas arrivals for as long as 14 days, and effectively bars flights from an array of countries deemed to be high risk - is sticking to a goal of eliminating the virus even as cases in the community surge.

Last week, the authorities there tightened restrictions even further, extending gathering limits to private premises for the first time.

And while Singapore has struck more than two dozen agreements with other countries to set up vaccinated travel lanes (VTLs), it still requires overseas visitors to undergo almost a week of daily coronavirus tests during their stay. Anyone attending the scaled-back Singapore Airshow this week must also test negative each day as a condition of entry.

These impediments to flying extend the financial pressure on airlines primarily plying routes in Asia, from Cathay Pacific Airways and Singapore Airlines to budget carriers Cebu Air in the Philippines and Malaysia's AirAsia.

While China holds the key to a broad recovery - its vast market could trigger a global travel resurgence all on its own - the country is expected to keep its borders sealed for most of this year at least.

The uneven air-travel rebound is likely to continue for the rest of 2022 as countries in Europe and North and South America continue to reopen and Asian restrictions put off travellers, according to Mr Rob Morris, Cirium's global consultancy chief.

"The two-speed recovery is very evident," he said. "A significant level of intra-Asia traffic touches China and with borders there likely to remain closed to international arrivals through late 2022, the recovery in Asia will inevitably be slower than other regions."

Choking the flow

Within Europe, flying will surpass 75 per cent of pre-pandemic levels next month, according to Cirium data from airline schedules. Inside the US, the figure will be 86 per cent.

Asia's Covid-19 curbs are choking the flow of visitors to the countries that need them most. Australia's Jetstar recently delayed a resumption of flights to Bali from Melbourne and Sydney, citing the island's five-day quarantine requirement for vaccinated arrivals.

"We look forward to flying into Bali when quarantine restrictions ease further," said Jetstar, which is owned by Qantas Airways.

Thailand this month resumed quarantine-free tourism for vaccinated travellers. But the programme's requirements for multiple tests, registration and a certain baseline of insurance cover have drawn criticism. Thailand expects fewer than 10 million foreign visitors this year, down from 40 million before the virus.

"The testing requirements are a disincentive," said Ms Hannah Pearson, founding partner of Kuala Lumpur-based tourism consultancy Pear Anderson. "The fact that Singapore and Thailand, the two leaders of reopening in the region, are still taking this intense approach to testing, may encourage other countries to behave similarly."

The cost of daily swabbing for a family visiting Singapore is prohibitive enough, said Ms Pearson. The mandatory test on arrival is $125. On top of that, visitors run the risk of returning a positive result, then paying to quarantine in a hotel and wasting their trip, she said.

No tests

At some point, South-east Asia's tourist hubs will need to demand less of overseas visitors, Ms Pearson said. That might mean downgrading to a rapid antigen test on arrival, or waiving tests completely for those who already recorded a negative result before they took off, she said.

China and Hong Kong, meanwhile, are showing no sign of giving up their battle to contain the virus, even as other parts of the world treat it as endemic. Chinese authorities this month locked down 3.6 million residents of the south-western city of Baise after identifying fewer than 100 cases.

The central role that China and Hong Kong play in Asia's aviation market means their Covid-zero approach weighs on neighbouring nations. The number of scheduled flights into all of Asia from outside the region this month is little more than half the total before the pandemic, Cirium data show.

The reluctance of travellers to tolerate quarantine after they land is clear: It typically deters at least 90 per cent of potential passengers, Auckland International Airport said this month, citing the experience of airlines in other markets.

The speed at which passengers return to the air once restrictions and mandatory tests are removed also indicates how much these rules hinder travel.

British Airways and Virgin Atlantic Airways, for example, reported a surge of interest in long-haul flights in January. That was just days after a requirement that vaccinated arrivals take a Covid-19 test before boarding a flight into England was dropped.

On Feb 11, Britain also stopped requiring vaccinated travellers to take a Covid-19 test after arriving in England.

'Spreading widely'

The British government is now depending on vaccines as it takes steps to live with the virus, recognising inoculation certificates from over 180 countries and territories.

The Omicron variant is already "spreading widely in the community", the government said as it made the change. Testing incoming vaccinated travellers, UK Transport Secretary Grant Shapps said, had "outlived its usefulness".

Buoyed by that decision, the aviation industry is lobbying the US government to scrap pre-departure tests for incoming vaccinated passengers there as well.

In a Feb 2 letter to the White House, travel industry groups led by Airlines for America argued Covid-19 was already widespread in the US, and pre-flight tests "are unlikely to change that fact".

The letter cited Britain as a precedent, as well as the European Union's January recommendation that member states remove intra-Europe Covid-19 travel restrictions.

Destinations in Asia are likely to continue to struggle to lure travellers for short breaks, said lecturer Volodymyr Bilotkach, associate professor in air-transport management at the Singapore Institute of Technology.

"Why come to Singapore for four to five days and pay for all the extra tests facing the risk of being stuck in your hotel room, when you can go to New York without having to worry about all this stuff?" he said.