A couple covered in mud wait for it to dry at the Salt-works lakes near the Black Sea town of Burgas in Bulgaria on July 25, 2019. Thousands of tourists visit the red salt lakes for mud baths, which are believed to help the healing of muscular disorders and rheumatism. (Photo by Nikolay Doychinov/AFP Photo)

Leo, an orphaned Sumatran orangutan, is taken to the Sumatran Orangutan Conservation Programme rehabilitation centre. Leo will join other orangutans who have been reintroduced to the Pinus Jantho nature reserve. The SOCP has gradually formed a completely new wild population of species that have been threatened with extinction. (Photo by Sutanta Aditya/Barcroft Images)

Protesters begin to gather ahead of the UK Student Climate Network's Global Climate Strike at Millbank in London, England on September 20, 2019. (Photo by Gareth Fuller/PA Images via Getty Images)

Scott Meiklejohn gets into character as a mummy during a photo call on October 10, 2019 in Stirling, Scotland ahead of “Hallowild”, Blair Drummond Safari Parks annual Halloween event. This years theme in the haunted walkway is an egyptian tomb with special 3D effects alongside actors playing the roles of Pharaohs and Mummies. (Photo by Andrew Milligan/PA Images via Getty Images)

A Kurdish fighter from the People's Protection Units (YPG) fires his rifle at Islamic State militants as he runs across a street in Raqqa, Syria, July 2017. (Photo by Goran Tomasevic/Reuters)

A man wearing a hazmat suit and a mask holds a sign reading “The end is near – call grandma” at Times Square on March 14, 2020 in New York City. The World Health Organization said March 13, 2020 it was not yet possible to say when the COVID-19 pandemic, which has killed more than 5,000 people worldwide, will peak. “It's impossible for us to say when this will peak globally”, Maria Van Kerkhove, who heads the WHO's emerging diseases unit, told a virtual press conference, adding that “we hope that it is sooner rather than later”. (Photo by Johannes Eisele/AFP Photo)

A woman uses a face masks as a preventive measure against the spread of the new coronavirus, COVID-19, in Bogota, on March 19, 2020. Colombia will block all international flights from Monday for 30 days, President Ivan Duque announced on Thursday. (Photo by Raul Arboleda/AFP Photo)

An air plane takes off from the airport as air traffic is effected by the spread of the coronavirus disease (COVID-19) in Frankfurt, Germany, March 16, 2020. (Photo by Kai Pfaffenbach/Reuters)