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)

Ivanelis Jimenez, front, and Veronica Barreto pose for the camera wearing Puerto Rican flag dresses as they welcome passengers exiting Carnival's Mardi Gras cruise ship, docked in the bay of San Juan, Puerto Rico, Tuesday, August 3, 2021, marking the first time a cruise ship visits the U.S. territory since the COVID-19 pandemic began. (Photo by Carlos Giusti/AP Photo)

An indigenous man of Mahmeri tribe wearing a costume of Puteri Gunung Ledang character receives a dose of the vaccine against Covid-19 in Banting, near Kuala Lumpur, Malaysia,15 August 2021. Malaysia recorded another 20,670 new Covid-19 cases on 14 August, bringing the cumulative total to 1,384,353 cases. (Photo by Ahmad Yusni/EPA/EFE)

Students wearing masks as a precaution amid the spread of COVID-19 put away a Cuban flag so it does not get wet in the rain on their first day of school after months without face-to-face classes in Havana, Cuba, Monday, November 8, 2021. As Cuba approaches the announced date of Nov. 15 for the reopening of the entire country to the world, getting children back to school is one of its priorities. (Photo by Ramon Espinosa/AP Photo)

A pedestrian wearing a face mask to protect against coronavirus, walks in front of a mural, at a metro station in Athens, Greece, Monday, November 15, 2021. Authorities say the rate of death related to COVID-19 in Greece has reached its highest level in six months as roughly one-third of the country's population remains unvaccinated. (Photo by Thanassis Stavrakis/AP Photo)

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)

A man wearing a face mask walks his dog as he pulls a trolley after shopping in Beijing on February 13, 2020. The number of deaths and new cases from China's COVID-19 coronavirus outbreak spiked dramatically on February 13 after authorities changed the way they count infections in a move that will likely fuel speculation that the severity of the outbreak has been under-reported. (Photo by AFP Photo/China Stringer Network)

In this Sunday, February 23, 2020, photo, sumo wrestlers wearing masks arrive at Shin Osaka railway station in Osaka, western Japan. A viral outbreak that began in China has infected more than 79,000 people globally. The World Health Organization has named the illness COVID-19, referring to its origin late last year and the coronavirus that causes it. (Photo by Kyodo News via AP Photo)