Rwandan refugees cross the Rusumo border to Tanzania from Rwanda carrying their belongings, goats, mattresses and cows, May 30, 1994. The bloodshed that claimed 800,000 Tutsi and moderate Hutu lives began 25 years ago on April 7, 1994, when a plane carrying Rwandan President Juvenal Habyarimana, Burundi President Cyprien Ntaryamira and a French air crew was shot down. (Photo by Jeremiah Kamau/Reuters)

Pedestrians and traffic cross Tower Bridge as viewed through a glass viewing platform on the high-level Walkways during a preview to launch the new viewing experience at the Tower Bridge Exhibition centre in London on November 10, 2014. The new glass flooring at the Tower Bridge Exhibition 42 metres above the river Thames will allow visitors to gaze down on the bridge and river and allow them to experience the bridge opening from above. (Photo by Andrew Cowie/AFP Photo)

Protesters wear masks, the left in the colors of the Kenyan national flag, as they join others carrying mock coffins and red-painted crosses, symbolizing the blood of the 28 non-Muslims singled out and killed in the recent attack on a bus in Mandera by Somali militant group al-Shabab, outside government offices in downtown Nairobi, Kenya Tuesday, November 25, 2014. (Photo by Ben Curtis/AP Photo)

Children fall as they slide down on a float along a chute to cross a pool of water and foam during the “Letniy Gornoluzhnik” (Summer mountain puddle rider) festival at the Bobroviy Log Fun Park near the Siberian city of Krasnoyarsk, Russia, August 23, 2015. The annual competition marks the end of the summer season at the Siberian ski, rest and entertainment resort. (Photo by Ilya Naymushin/Reuters)

Migrants wait to cross the Slovenia-Austria border in Sentilj, Slovenia, October 27, 2015. The first five border guards – all German – of 400 promised to Slovenia by fellow EU countries are expected to arrive on Wednesday to help channel a huge flow of migrants through the tiny Alpine state, its government said. Interior Ministry state secretary Bostjan Sefic also said 100-120 customs police would join Slovenian soldiers, regular police and private security firms in dealing with an influx that has strapped the country's limited resources. (Photo by Srdjan Zivulovic/Reuters)

Genko Stoykov fires a rifle as he and other men prepare for the traditional “Horo” dance on Epiphany Day in the icy winter waters of the Tundzha river on January 6, 2022 in Kalofer, Bulgaria. As part of the tradition, a priest throws a cross in the river and it is believed that the one who retrieves it will be healthy throughout the year. Today, cultures throughout Christendom mark the Feast of the Epiphany, when Jesus was revealed to the Magi as God incarnate. (Photo by Hristo Rusev/Getty Images)

Five-year-old sniffing dog “Vine” wears protection goggles against the sun and dust as he poses together with Giulia Gausemann for photographers, at the sniffing dogs school of the German Army (Bundeswehr) in Daun, Germany, July 24, 2020. The Bundeswehr sniffing dogs school and the veterinarian university of Hanover are developing a training programme to sniff out the coronavirus disease (COVID-19) with dogs at airports, border crossings and other highly frequented places. (Photo by Wolfgang Rattay/Reuters)

A vegetable vendor wearing gloves and face mask as a precaution against the coronavirus interacts with a customer in Bengaluru, India, Sunday, October 11, 2020. India's confirmed coronavirus toll crossed 7 million on Sunday with a number of new cases dipping in recent weeks, even as health experts warn of mask and distancing fatigue setting in. (Photo by Aijaz Rahi/AP Photo)