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)

In this Thursday, February 14, 2019, photo, a Transformer's Bumblebee mascot helps a woman carries paper bags at a shopping mall in Handan in north China's Hebei province. U.S. and Chinese envoys are holding a second day of trade talks after the top economic adviser to President Donald Trump said he has yet to decide whether to go ahead with a March 2 tariff increase on imports from China. (Photo by Chinatopix via AP Photo)

A Saudi police officer receives emergency calls at a call center, ahead of the Hajj pilgrimage in the Muslim holy city of Mecca, Saudi Arabia, Tuesday, August 6, 2019. The hajj occurs once a year during the Islamic lunar month of Dhul-Hijja, the 12th and final month of the Islamic calendar year. (Photo by Amr Nabil/AP Photo)

Honourable mention, Behaviour category. Toss the scorpion – Indian roller playing with its kill by Susmita Datta. The image was taken during an early morning safari drive at Tadoba Andhari Tiger Reserve in India. (Photo by Susmita Datta/PA Wire/Royal Society Publishing Photography Competition 2017)

Aerial view of pond cypress at Qinglongwan Forest Park near Ningguo, China on November 26, 2017. (Photo by Imaginechina/Rex Features/Shutterstock)

Kritchaya “Lolita” Boonhor (R) curls her eyelashes in ladyboy Candy's (L) room while she chats her about her boyfriend, in Bangkok, Thailand, 27 November 2017. Most things in life are a question of negotiation. Lolita is a woman, that was not to be negotiated. What needed to be negotiated was how she was perceived by those around her. And that negotiation was one that took time and effort. (Photo by Lola Levan/EPA/EFE)

Firefighters pull a pig as they try to rescue it from a well at a pig farm in Huanghua township of Leqing, Zhejiang province, China, April 25, 2014. Seven local firefighters successfully rescued the 300 kg (661 lbs) pig, local media reported. (Photo by Reuters/China Daily)

Rohingya refugee sisters Nur Kaida (R) and Ruhana hug each other at their shelter at the Palongkhali refugee camp near Cox's Bazar, Bangladesh December 21, 2017. (Photo by Marko Djurica/Reuters)