Photos show what happened during polio outbreaks in the US and how the vaccine was developed. A virus that affects nerves in the spinal cord or brain stem causes polio. Polio mainly affects ...

(Getty Images) Dr. Li Wenliang lies on a bed at Wuhan ... the world as they try to lure back clientele while keeping them virus-free. (Thibault Camus / AP) Diners sit under a plastic shield ...

Many businesses in the city have reopened, including the “wet markets” where the virus is thought to have originated. These markets are where wild animals are slaughtered and sold.