Commuters wear protective face masks as they walk through a subway station, in Sao Paulo, Brazil, Wednesday, December 1, 2021, amid the COVID-19 pandemic. Brazil joined the widening circle of countries to report cases of the omicron variant. (Photo by Andre Penner/AP Photo)

An a music therapist plays harp during treatment of patients suffering from the coronavirus disease (COVID-19) in the Intensive Care Unit (ICU) at Havelhoehe community hospital in Berlin, Germany, December 6, 2021. (Photo by Fabrizio Bensch/Reuters)

Dancer of the Berlin State Ballet (Staatsballett Berlin) wear face masks as they perform during the dress rehearsal of Don Quixote in a production choreographed by Victor Ullate, amid the coronavirus disease (COVID-19) pandemic at Deutsche Oper opera house in Berlin, Germany, December 1, 2021. (Photo by Fabrizio Bensch/Reuters)

Kite-surfers practice in a water reservoir at the shores of the Mediterranean sea close to the southern Israeli kibbutz of Ziqim during stormy weather, on December 20, 2021. (Photo by Menahem Kahana/AFP Photo)

A Palestinian man dressed as Santa Claus gestures as he rides a camel in Jerusalem's Old City during Christmas celebrations, on December 23, 2021. (Photo by Ahmad Gharabli/AFP Photo)

Revellers make the most of Boxing Day in Liverpool city centre, United Kingdom on Sunday, December 26, 2021. Boxing Day is a holiday celebrated after Christmas Day, occurring on the second day of Christmastide. (Photo by London News Pictures)

Revellers take part in the Els Enfarinats festival, in the town of Ibi near Alicante, Spain, Tuesday December 28, 2021. For about 200-years the inhabitants of Ibi annually celebrate with a battle using flour, eggs and firecrackers, outside the city town hall. (Photo by Alberto Saiz/AP Photo)

Revellers enjoying the pubs and clubs in Leeds despite concerns over Omicron on December 10, 2021. Festive revellers have hit the pubs and clubs across the UK tonight as Plan B rules come into force and fears grow over the spread of Omicron. (Photo by Nb press ltd)