An Afghan policeman frisks a man while a burqa-cald woman sits in the trunk of a car on a roadside in Herat, Afghanistan, 05 July 2015. At least 18 police, two civilians and 30 rebels were killed in central Afghanistan during three days of fierce fighting, police said on 04 July. The clashes ended 04 July after security forces retook control of nine police checkpoints that had fallen to the rebels. (Photo by Jalil Rezayee/EPA)

Seven-year-old Mimi Meade winces from the sting as Dr. Richard Mulvaney inoculates her April 26, 1954 in McClean, Va., with the new Salk polio vaccine. Mrs. John Lucas, a registered nurse, holds Mimi's arm steady as she gets one of the first injections of the countrywide test. (Photo by Harvey Georges/AP Photo)

The rising sun illuminates the sky above the spires of a church in Vienna, Austria, November 17, 2015. (Photo by Heinz-Peter Bader/Reuters)

Dancers pose after performing “El Macho Raton”, “El Toro Huaco” and “El Gueguense” traditional dances during San Sebastian festivity in Diriamba, province of Carazo, some 50 km south of Managua on January 19, 2016. Devotees of Saint Sebastian dance in traditional costumes between the cities of Diriamba and Dolores, which are some three kilometers away. (Photo by Inti Ocon/AFP Photo)

Pope Francis greets the crowd from his popemobile in downtown Rio de Janeiro. Pope Francis touched down in Rio de Janeiro on Monday, starting his first foreign trip as pontiff and a weeklong series of events expected to attract more than a million people to a gathering of young faithful in Brazil, home to the world's largest Roman Catholic population. (Photo by Ueslei Marcelino/Reuters)

Singers Britney Spears and Madonna share a kiss onstage during the 2003 MTV Video Music Awards at Radio City Music Hall on August 28, 2003 in New York City. (Photo by Dave Hogan/Getty Images)

A woman participates in the “Carnaval na Central” block party in Rio. (Photo by Felipe Dana/Associated Press)

Alicia Vargas, 23, a performer from the Urus Diablada group, tied the laces of her boots before a practice ahead of Carnival in Oruro, Bolivia February 5, 2016. (Photo by David Mercado/Reuters)