Thousands of flights around the world have been canceled for the Christmas weekend as the Omicron variant infections continue to surge.

Airlines have blamed shortages of healthy staff for the cancellations of nearly 2,400 flights on December 24 and more than 2,300 on December 25.

More than 800 of those canceled on December 25 were to or from US airports.

In Europe, travel restrictions are among measures aimed at reducing cases, largely driven by the Omicron variant.

Despite early findings that Omicron is milder than other variants, scientists are concerned by the sheer number of infections being recorded.

Many of the flight cancellations are the result of airline crews testing positive, or being forced to self-isolate to stem the spread.

Further delays and disruption is expected with hundreds more flights canceled on December 26, according to website FlightAware.

The US, like many countries around the world, has seen a sharp rise in cases.

Across Europe, governments are bringing in their own measures to combat the increase:

• Italy, Spain and Greece have made face masks compulsory outdoors again
• Catalonia, in north-eastern Spain, has imposed an overnight curfew
• The Netherlands entered a strict lockdown earlier this week
• Germany has said it will restrict private gatherings to 10 people and close nightclubs from December 28. Soccer matches will be played behind closed doors
• Portugal has ordered bars and nightclubs to shut from December 26, and made working from home obligatory until January 9.

However, in South Africa – where the Omicron variant was first identified – the government has ended Covid contact tracing, except for serious cluster outbreaks or prisons.

The health department announced that as most of the population had now been exposed to the coronavirus, the policy is now shifting from a containment strategy to one of mitigation including self-monitoring, mask wearing and social distancing.

The US earlier announced it would lift travel restrictions imposed on South Africa and seven other African countries because of concerns about the Omicron variant on December 31.

Travelers from South Africa, Botswana, Zimbabwe, Namibia, Lesotho, Eswatini, Mozambique and Malawi had been blocked since November 29.

America’s top infectious disease expert, Dr. Anthony Fauci, warned earlier this week that Christmas travel would increase the spread of the variant even among the fully vaccinated.

However, thousands found their plans thrown into disarray as flights across the country were cancelled or delayed.

The worst affected US companies are Delta, United Airlines and American Airlines.

United Airlines said rising numbers of Omicron cases had “had a direct impact on our flight crews and the people who run our operation”, adding that it was contacting impacted passengers in advance of them coming to the airport.

Overall, global airlines have cancelled more 4,700 flights scheduled to take off on Friday and Saturday.

In Australia, thousands of festive journeys were affected on December 24 with more than 100 domestic flights from Sydney and Melbourne to other cities cancelled.

More than 5.3 million people have died with coronavirus worldwide, according to America’s Johns Hopkins University. There have been 279 million confirmed cases.