A similar vaccine, being developed at the University of Oxford, UK, was also named as a priority for testing during a Marburg outbreak. Teresa Lambe, a vaccinologist at Oxford leading the Marburg vaccine’s development, says that the vaccine has so far proven safe in the handful of participants who have received it in an ongoing UK trial.

The Ebola-related Marburg virus kills around half of those infected but has been fatal in up to 90 per cent of cases.

The U.S.Centers for Disease Control and Prevention on Monday said it was in conversation with Rwandan health officials amid an outbreak of Marburg virus.