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 woman cools off at a fountain in central Cordoba, southern Spain, 11 August 2021. Andalucia was put on orange alert for high temperatures, with a new heatwave forecast to reach temperatures of over 41 degrees Celsius in the region. (Photo by Salas/EPA/EFE)

A masked dancer performs as part of “Devi Pyankha” (Devi Dance) to mark the beginning of the Indra Jatra Festival in Kathmandu, Nepal on September 15, 2021. Nepali celebrate the Indra Jatra festival to worship “Indra”, the god of rain and to mark the end of monsoon season. (Photo by Sunil Sharma/ZUMA Press Wire/Rex Features/Shutterstock)

Postal worker Eddie Smith, dressed as Santa Claus, waves to a neighbor on his mail route in Washington, U.S., December 21, 2021. (Photo by Evelyn Hockstein/Reuters)

People participate in the Cordao do Boitata carnival celebration in the Centro City neighborhood on February 16, 2020 in Rio de Janeiro, Brazil. (Photo by Bruna Prado/Getty Images)

An NHS worker walks past a banner supporting NHS staff outside Salford Royal Hospital on March 22, 2020 in Manchester, UK. Coronavirus (COVID-19) has spread to at least 182 countries, claiming over 13,069 lives and infecting more than 308,592 people. There have now been 5,018 diagnosed cases in the UK and 233 deaths. (Photo by Anthony Devlin/Getty Images)

A police officer chases shoppers to clear the streets of the Red Light market on the first day of lockdown to stop the spread of the coronavirus disease (COVID-19) in Monrovia, Liberia on April 11, 2020. (Photo by Derick Snyder/Reuters)

People take photos of hotel room lights shaping the word “Zero”, referring to Covid-19 cases, in Taipei, Taiwan, 17 April 2020. According to news reports Taiwan records no new COVID-19 cases for third time this week. Medical experts are rushing to develop a vaccine for the COVID-19 disease caused by the SARS-CoV-2 coronavirus and advising people to practice social distancing and proper hygiene. (Photo by David Chang/EPA/EFE/Rex Features/Shutterstock)