The tragic death of a young Liberian boy has proven that women are capable of hosting and spreading the deadly Ebola virus.

Just after what seemed to be the final days of the West Africa Ebola epidemic — which killed 11,325 of the approximately 28,600 infected — a family brought in their 15-year-old son vomiting blood. He was diagnosed as a victim of the Ebola virus and died ten days later, despite all efforts at treatment.

Immediately, medical “contact tracers” brought his family in for testing, and vaccinated the roughly 120 people at risk of infection through contact with them. The boy’s father and eldest younger brother tested positive but were treated and recovered. The middle brother, just five years old, showed no trace of the virus and was able to be vaccinated along with the others.

It was the mother and baby that provided new insight. Neither had Ebola, but both possessed antibodies capable of fighting it. Epidemiologist Dr. Emily Kainne Dokubo and her colleagues at the Centers for Disease Control (CDC) believe that the woman’s previous miscarriage exposed her to the virus, and that her second pregnancy weakened her immune system enough to make it transmissible to her family.

Fortunately, the surviving family members were the first members of a clinical trial for an Ebola vaccine that has already been used to save thousands of lives during an outbreak in the Democratic Republic of Congo. Still, Dokubo and her peers worry about the stigma surrounding potential Ebola victims.

Lorenzo Subissi, an Ebola expert at Sciensano, Belgium’s public health institute, fears that the results of the study “could lead to additional stigma around survivors,” who are already routinely run from their homes and communities for fear of the deadly virus. He hopes that the vaccine can be used not only to stop outbreaks, but to give peace of mind to the people who live through them.

For now, West Africa’s war with Ebola has ended. Despite this grim new revelation of its potency, scientists continue to work tirelessly toward its total eradication. If all goes well, the vaccine may represent a major step in that direction.