It isn’t often when an invention that changes the landscape comes along. But one just did.

A new paper in the British journal TheLancet, which had 30 authors, reports results that seem too good to be true.

But they are not. A group led by the World Health Organization using a vaccine that was invented in Canada conducted a large scale inoculation in Guinea and Sierra Leone to assess how well it protected people against Ebola—the virus that ravaged Africa in 2014, killing 60 percent of the people that it infected. How well did it work? Spectacularly. The vaccine protected 100 percent of the people who received it. This is the first and only therapy for Ebola, other than prior supportive measures such as rehydration.

Original source: Henaro-Restrepo et al “Efficacy and effectiveness of an rVSV-vectored vaccine in preventing Ebola virus disease: final results from the Guinea ring vaccination, open-label, cluster-randomised trial (Ebola Ça Suffit!)” The Lancet (2016) Volume 388, Online First.