A woman cries as she watches a building burn after a protest over the death of George Floyd, Sunday, May 31, 2020, in La Mesa, Calif. Protests were held in U.S. cities over the death of Floyd, a black man who died after being restrained by Minneapolis police officers on May 25. (Photo by Gregory Bull/AP Photo)

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)

Dutch cyclist Fabio Jakobsen's bicycle (behind, L) flies through the air as he collides with compatriot Dylan Groenewegen (on the ground, L) during the opening stage of the Tour of Poland race in Katowice, southern Poland on August 5, 2020. The Dutch rider was fighting for his life on Wednesday after he was thrown into and over a barrier at 80km/h in a sickening conclusion to the opening stage of the Tour of Poland. (Photo by Szymon Gruchalski/Forum/AFP Photo)

A boy looks for scrap metal using an improvised magnetic tool near a construction site in New Delhi, India, March 21, 2016. (Photo by Cathal McNaughton/Reuters)

A Perseid meteor streaks across the sky above Inspiration Point early on August 12, 2016 in Bryce Canyon National Park, Utah. The annual display, known as the Perseid shower because the meteors appear to radiate from the constellation Perseus in the northeastern sky, is a result of Earth's orbit passing through debris from the comet Swift-Tuttle. (Photo by Ethan Miller/Getty Images)

A man poses in front of a portrait of late Chinese Chairman Mao Zedong during the opening of an exhibition of Mao related art in Beijing, China, September 8, 2016. (Photo by Thomas Peter/Reuters)

A veterinarian from the zoo of Besancon feeds “Soa”, a female crowned sifaka, in Besancon, eastern France, on February 18, 2019. The crowned sifaka is a critically endangered species from Madagascar. There were only 6 females over 20 individuals living in 7 zoos worldwide end of 2018. (Photo by Sébastien Bozon/AFP Photo)