Airlines around the world cancelled more than 4,500 flights over the Christmas weekend, as a mounting wave of COVID-19 infections created greater uncertainty and misery for travellers.
Carriers scrapped at least 2,401 flights on Friday, which fell on Christmas Eve and is typically a heavy day for air travel, according to a running tally on the flight-tracking website FlightAware.com.
The website showed that 1,779 Christmas Day flights were called off worldwide, along with 402 more that had been scheduled for Sunday.
Among the first US carriers to report a wave of holiday weekend cancellations were United Airlines and Delta Air Lines, which collectively scrubbed nearly 280 flights on Friday alone, citing personnel shortages amid the surge of COVID-19 infections.
COVID-19 infections have increased in the United States in recent days due to the highly transmissible variant Omicron, which was first detected in November and now accounts for nearly three-quarters of US cases and as many as 90 per cent in some areas.
New York reported more than 44,000 newly confirmed infections on Friday alone, shattering that state's daily record. At least 10 other states set new one-day case records on Thursday or Friday.
In the UK, many industries and transport networks were struggling with staff shortages as sick workers self-isolated, while hospitals have warned of the risk of an impact on patient safety.
One in 20 Londoners had COVID-19 last week, a figure that could rise to one in 10 by early next week, according to data released on Thursday by the Office for National Statistics.
New South Wales amid concern over the spread of the Omicron variant, while Victoria had 2,108 new cases.
While recent research suggests Omicron produces milder illness - and a lower rate of hospitalisations - than previous variants of COVID-19, health officials have maintained a cautious note about the outlook.
"There is a glimmer of Christmas hope ... but it definitely isn't yet at the point where we could downgrade that serious threat," Jenny Harries, head of the UK Health Security Agency, told the BBC.
France hit another COVID-19 infection record on Friday, with its daily tally exceeding 94,000 while hospitalisations from the virus reached a seven-month high, prompting the government to convene a special meeting for Monday that could trigger new public health restrictions.
Despite the uncertainties and grim news around the world, millions of Americans carried on with travel plans through a second pandemic-clouded holiday season.
Dozens of Broadway shows have been cancelled as Omicrom spreads. Source: Sipa USA John Nacion / SOPA Images/Sipa U
Moses Jimenez, an accountant from Long Beach, Mississippi, flew to New York with his wife and three children, even though the latest torrent of coronavirus cases dashed their hopes of catching a Broadway performance of Hamilton or visiting some museums.
Hamilton was one of a dozen productions to cancel shows this week as cast and crew members tested positive for COVID-19.
Instead, the 33-year-old said his family will make the best of roaming the city's streets and parks, while also seeing relatives and friends.
"We just wanted to get out of the house, really, get the kids out to the city for Christmas," Mr Jimenez told Reuters on Thursday at New York's LaGuardia Airport.
