No individuals who received the rVSV-ZEBOV vaccine as part of the Wellcome-funded trial developed Ebola, showing that it is very effective in preventing the deadly disease.
The study used an innovative trial design called ‘ring-vaccination’ – the same method used to successfully eradicate smallpox.
Wellcome Director Jeremy Farrar described the result as "a simply remarkable outcome".
The West African Ebola epidemic began in early 2014 and spread rapidly across Guinea, Sierra Leone and Liberia. More than 11,000 people died and over 28,000 people were infected.
The vaccine, made by Merck, Sharpe & Dohme, is the first to be shown to prevent Ebola infection. It was developed rapidly during the epidemic but came too late to have a significant impact on the outbreak.
"Had a vaccine been available earlier in the Ebola epidemic, thousands of lives might have been saved," adds Jeremy Farrar. "We have to get ahead of the curve and make promising diagnostics, drugs and vaccines for diseases we know could be a threat in the future."