Rwandan health authorities will begin a vaccine study against the Marburg hemorrhagic fever as the East African country tries to stop the spread of an outbreak that has killed 12 people.

A new vaccine trial is under way in Rwanda as the country fights an outbreak of the highly deadly Marburg virus.

The U.S. Centers for Disease Control and Prevention will issue its second-highest level of travel notice for Rwanda, recommending people to avoid nonessential travel due to the Marburg disease outbreak in the east African country,