Amid the rapidly increasing Covid-19 cases globally, fueled by the Omicron variant, as many as 11,500 flights have been cancelled worldwide since Friday.
The news comes during one of the year's busiest travel periods with multiple airlines blaming spikes in cases of the Omicron coronavirus variant for staff shortages.
Notably, cases in the United States are already on track to reach record highs in January.
Governments across the globe are scrambling to boost vaccination along with bringing back several curbs to halt the spread of the highly contagious Omicron variant.
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Several nations across Europe are reviving lockdowns while China is also desperate to keep a lid on the pandemic before February's Beijing Winter Olympics.
Some 13 million residents are already confined to their homes in Xi'an, where Covid controls were tightened Monday to the "strictest" level, banning residents from driving.