Chinese aids activists hand out condoms in a subway train in Wuhan, central China's Hubei province on December 1, 2014. The World Health Organization issued a call to action to China on December 1, 2014 over HIV/AIDS as government figures said nearly half a million people are living with the disease or its precursor, with hundreds of thousands more thought to be undiagnosed. (Photo by AFP Photo)

Saintsetseg Jambaldorj, a member of the Tsaatan ethnic minority, one of the last remaining groups of nomadic reindeer herders in East Taiga, Mongolia, wearing a traditional deel, on July 5, 2016. (Photo by Madoka Ikegami/Barcroft Images)

An Afghan journalist takes a “selfie” as U.S. President Barack Obama (R) holds a joint news conference with Afghanistan's President Ashraf Ghani (C) at the White House in Washington March 24, 2015. (Photo by Jonathan Ernst/Reuters)

John Klatt and the Air National Guard MXS (right) and Mike Wiskus and the Lucas Oil Pitts take to the skies at the Memphis Airshow, on Sat., September 26, 2016 in Millington, Tenn. (Photo by Brandon Dill/Invision for John Klatt Airshows, Inc./AP Images)

Yakelin Hernandez, 18, poses for a photograph near The Malecon where The Carnival was held, on August 14, 2015. Colorful costumes, dancing, parades and street parties on the Malecon in Havana, Cuba are all part of Havana Carnival 2015 which was held in August. (Photo by Sarah L. Voisin/The Washington Post)

A photo taken on August 29, 2014, shows Mount Tavurvur erupting in eastern Papua New Guinea, spewing rocks and ash into the air, forcing the evacuation of local communities and international flights to be re-routed. Mount Tavurvur, which destroyed the town of Rabaul when it erupted simultaneously with nearby Mount Vulcan in 1994, rumbled to life early in the morning on the tip of the remote island of New Britain. (Photo by Oliver Bluett/AFP Photo)

A girl dressed up as a emissary of the Three Wise Men poses for a photo as she waits for their arrival in a helicopter to take part in the traditional Epiphany parade in Ronda, Spain, January 5, 2018. (Photo by Jon Nazca/Reuters)

A masked reveller parades through the streets on the first day of the carnival season in Lucerne, Switzerland, 12 February 2015. In the background the well known Kappellbruecke bridge. (Photo by Alexandra Wey/EPA)