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)

Chinese aids activists hand out condoms in a subway train in Wuhan, central China's Hubei province on December 1, 2014. The World Health Organization issued a call to action to China on December 1, 2014 over HIV/AIDS as government figures said nearly half a million people are living with the disease or its precursor, with hundreds of thousands more thought to be undiagnosed. (Photo by AFP Photo)

A woman carries an umbrella during a heat wave in Rome, Italy, 16 July 2023. Italy is facing the third heatwave of the summer on 16 July bringing record temperatures. The new heatwave is forecast to peak on 18 July, when temperatures in areas of southern Sardinian may reach 48 degrees Celsius, according to forecasts. On 15 July, the health ministry has put on red alert major Italian cities. (Photo by Massimo Percossi/EPA)

Male members of the Zeleziar folk dance group whip and water the local girls dressed in traditional clothing, during Easter in Bociar, Slovakia on April 1, 2024. Boys and younger men visit the houses of young girls, whip them with fresh-cut decorated wickers and sprinkle water on them. By tradition, the whipping should give the girls strength, health, and abundance throughout the whole year. (Photo by Robert Nemeti/Anadolu via Getty Images)

Udomsak Ratanotayo, left, and Suttinan Boonsomkiat wear storm trooper costumes while donating blood at the Thai Red Cross in Bangkok, Thailand on Monday, April 28, 2014. Thai Star Wars fans will donate blood and give toys at an orphanage as part of a promotional campaign. (Photo by Sakchai Lalit/AP Photo)

A small section of the expanding remains of the Veil Nebula, a massive star that exploded about 8,000 years ago. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan. (Photo by Reuters/NASA/ESA/Hubble)