Commercial airlines around the world cancelled more than 4,500 flights over the Christmas weekend, as a mounting wave of Covid-19 infections driven by the Omicron variant created greater uncertainty and misery for holiday travellers, reports Reuters. Airline carriers globally 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. Nearly 10,000 more flights were delayed. The website showed that 1,779 Christmas Day flights were called off worldwide, along with 402 more that had been scheduled for Sunday. Portugal’s national health agency has said Omicron has become the dominant strain in the country where over 12,000 daily Covid-19 cases have been registered in the last 24 hours, AFP reports. “The Omicron variant is already dominant in Portugal,” the General Directorate of Health said, “accounting for 61.5 per cent of cases on December 22.” Portugal has recorded 11 deaths and 12,943 cases – a record since January 29. Portugal has made work from home compulsory, closed bars and discos and made face masks mandatory indoors. Travellers entering the country have to provide a negative PCR test within three days even if they are vaccinated. Japan’s Kyoto and Fukuoka prefectures have detected new infections involving the Omicron coronavirus variant, including cases of possible community transmission, according to a government representative and local media. Kyoto prefecture in western Japan found four new infections of the Omicron coronavirus variant, including three cases of suspected community transmission as their infection routes were unclear, Kyodo news agency reported. Governor Seitaro Hattori told a news conference that Southwestern Fukuoka prefecture confirmed one Omicron case that was a possible community transmission, Reuters reports. Xian in northwest China has reported an increase in daily Covid-19 infections and local companies have curtailed activity as the country’s latest Covid-19 hot spot enters its third day of lockdown, Reuters reports.