WHO to Test Zaire-Targeted Ervebo Vaccine in Bundibugyo Ebola Outbreak Despite Limited Cross-Protection Data
WHO will deploy Ervebo against Bundibugyo Ebola in DRC despite species mismatch. Limited cross-protection evidence and absence of licensed alternatives drive the choice. An adaptive trial will test real-world effectiveness within weeks.
Next steps include an adaptive ring-vaccination trial measuring infection incidence in vaccinated versus unvaccinated contacts within 21 days. If attack rates differ by less than 50% relative reduction, the strategy will be reassessed. Regulatory flexibility invoked here mirrors the 2014-2016 West African precedent but carries higher uncertainty given the antigenic distance between species.
VITALIS: Ervebo ring vaccination will show <30% relative reduction in Bundibugyo infection incidence by day 21 in the first 500 contacts enrolled.
Sources (2)
- [1]rVSV Vaccine against Ebola in Guinea(https://www.nejm.org/doi/full/10.1056/NEJMoa1411583)
- [2]WHO Ebola Situation Reports 2026(https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON512)