In this April 14, 2014 file photo, Hamamatou Harouna, 10, who lost the use of her legs to polio, crawls to the restroom on the grounds of the Catholic Church where she and hundreds of others found refuge after fleeing violence in her village, in Carnot, Central African Republic. Health authorities on Tuesday, August 25, 2020 are expected to declare the African continent free of the wild poliovirus after decades of effort, though cases of vaccine-derived polio are still sparking outbreaks of the paralyzing disease in more than a dozen countries. (Photo by Jerome Delay/AP Photo/File)

A Student of Yuba Pratibha School, wearing a face shield and masks at school during a coronavirus pandemic in Kathmandu, Nepal, 26 November 2020. The head Teacher of Yuba Pratibha School, Yanga Raj Dahal, started to conduct classes for students, who can’t afford and attend online classes, with strict sanitary regime, providing also free face masks and shields for students. However majority of schools have been conducting online classes in Nepal from 19 March 2020 as part of precautionary measures against the spread of the coronavirus Covid-19. (Photo by Narendra Shrestha/EPA/EFE)

A Waura Indian woman watches the activities of this year's “quarup”, a ritual held over several days to honour in death a person of great importance to them, in Xingu National Park, Mato Grosso State, August 24, 2013. This year the Waura tribe is honouring their late cacique (chief) Atamai, who died in 2012 and helped created the Xingu Park, and his important contribution in facilitating communication between white Brazilians and Indians. (Photo by Ueslei Marcelino/Reuters)

“Diver in Magic Kingdom”. Green Lake (Grüner See) is located Tragöss Austria. In spring snowmelt raises the lake level about 10 meters. This phenomenon, which lasts only a few weeks covering the hiking trails, meadows, trees. The result is magical to watch diving landscapes. Photo location: Grüner See at Tragöss, Austria. (Photo and caption by Marc Henauer/National Geographic Photo Contest)

A woman cries as she watches the coffin containing the body of Venezuela's late President Hugo Chavez be taken from the hospital, where he died on Tuesday, to a military academy in Caracas, Venezuela, Wednesday, March 6, 2013. Seven days of mourning were declared, all schools were suspended for the week and friendly heads of state were expected for an elaborate funeral on Friday. (Photo by Rodrigo Abd/AP Photo)

President Barack Obama watches as Joey Hudy (L), 14, from Phoenix, Arizona pumps the Extreme Marshmallow Cannon he invented, while touring student science fair projects on exhibit in the State Dining Room at the White House February 7, 2012 in Washington, DC. Obama hosted the second White House Science Fair celebrating the student winners of science, technology, engineering and math (STEM) competitions from across the country. (Photo by Molly Riley-Pool/Getty Images)

Tourists gather to watch Mount Agung at Amed beach in Karangasem on Indonesia' s resort island of Bali on November 30, 2017. Thousands of foreign tourists were expected to leave Bali by plane on November 30 following a nearly three- day airport shutdown sparked by a rumbling volcano on the Indonesian holiday island. (Photo by Juni Kriswanto/AFP Photo)

Lu Wei-ming (L), priest of the Wei-ming temple, and a worshipper burn a Taoist paper amulet during a prayer ritual at the temple in New Taipei city January 8, 2015. The shrine, down a narrow alleyway in a bustling district of the city, is dedicated to a deity who has watched over homosexuals for four centuries. Priest Lu founded the temple in 2006, at a time gays were excluded from most religious ceremonies. (Photo by Pichi Chuang/Reuters)