A woman waits at a polio immunisation health centre, in Maiduguri, Borno State, Nigeria, August 29, 2016. Nigeria's military has liberated large swathes of land from Boko Haram but a ride with an army convoy, all guns firing for fear of ambush, shows how far the northeast is from normality after a brutal Islamist insurgency that has displaced millions. (Photo by Afolabi Sotunde/Reuters)

A weeping South Vietnamese mother and her three children are shown on the deck of this amphibious command ship being plucked out of Saigon by U.S. Marine helicopters in Vietnam, April 29, 1975. (Photo by AP Photo)

Revellers in Newcastle, England on the last Friday before Christmas, December 20, 2019. Black Eye Friday festive mayhem hit the nation; Christmas celebrations kicked off with a bang across the country as revellers flocked to pubs and clubs for the biggest night of the year. (Photo by Scott Heppell/PA Images via Getty Images)

Revellers take part in the Els Enfarinats festival, in the town of Ibi near Alicante, Spain, Saturday December 28, 2019. For about 200-years the inhabitants of Ibi annually celebrate with a battle using flour, eggs and firecrackers, outside the city town hall. (Photo by Alberto Saiz/AP Photo)

Penitentiary system guards carry an inmate with symptoms related to the novel coronavirus at the COVID-19 unit of San Juan de Dios hospital in Guatemala City on July 13, 2020. (Photo by Johan Ordonez/AFP Photo)

A mason bee deposits its collected pollen in an elderberry stick near Hessen, Germany on March 27, 2020. The food supply is sufficient for the eleven-month development of the brood from the egg to the finished bee. Wild bees are active in March and April and die before their offspring hatch. (Photo by Arne Dedert/dpa)

Natalie Duran, wearing a mask and dressed as Catwoman, climbs on street lights in SoHo as the city continues Phase 4 of re-opening following restrictions imposed to slow the spread of coronavirus on July 25, 2020 in New York City. The fourth phase allows outdoor arts and entertainment, sporting events without fans and media production. (Photo by Alexi Rosenfeld/Getty Images)

A reveler takes part in the 19th Gay Pride Parade at downtown Caracas, Venezuela on June 30, 2019. (Photo by Federico Parra/AFP Photo)