Revellers in Leeds, United Kingdom were excited to be out and about again on July 18, 2021. At a minute past midnight, England dropped most of its remaining Covid-19 social restrictions, such as those requiring indoor mask-wearing and limits on group gatherings. These changes come despite rising infections, pitting the country's vaccination programme against the virus's more contagious Delta variant. (Photo by Ioannis Alexopoulos/PA Wire Press Association via Getty Images)

A bakery worker carries fresh bread in Cairo, Egypt on August 1, 2021. (Photo by Amr Abdallah Dalsh/Reuters)

Hot-air balloons float over the Oka River during the Russian Sky International Balloon Festival in Ryazan Region, Russia on July 26, 2021. (Photo by Alexander Ryumin/TASS)

Bicycle rickshaw drivers chat as they wait for customers near the Drum Tower in a traditional neighbourhood on September 30, 2021 in Beijing, China. China will mark National Day and the Golden Week holiday from October 1st. (Photo by Kevin Frayer/Getty Images)

English actress and model Gemma Chan attends the “Eternals” red carpet during the 16th Rome Film Fest 2021 on October 24, 2021 in Rome, Italy. (Photo by Massimo Valicchia/NurPhoto/Rex Features/Shutterstock)

General view of the atmosphere at the Halloween celebrating in city centre on October 29, 2021 in Newcastle, United Kingdom. (Photo by Newcastle New Projects)

Pedestrians wear masks as smoke and haze from bushfires in New South Wales blankets the CBD in Sydney, Australia, 10 December 2019. The New South Wales environment department says visibility across east and southwest Sydney was at a “hazardous” level on Tuesday morning, while air quality was poor in southwest Sydney and hazardous in northwest Sydney. (Photo by Steven Saphore/EPA/EFE)

British Prime Minister Boris Johnson visits the Pavegen stand, a company that converts footsteps into energy, at the Innovation Zone during the UK-Africa Investment Summit in London, Britain on January 20, 2020. (Photo by Leon Neal/Pool via Reuters)