The bravery of the volunteers treating Ebola patients is immense. They are at serious risk of catching Ebola from the patients they treat.
Thirty thousand of these volunteers will be given a vaccine in a trial. The vaccine uses parts of the Ebola virus to trick the body into producing antibodies that will fight the infection.
The vaccine has been proved safe in smaller trials, but it's not known how effective it will be in protecting these amazing volunteers. I'm not sure I'd have the courage to do their dangerous work - with or without the vaccine.