The Coalition for Epidemic Preparedness Innovations (CEPI) announced on Friday 31 July that a vaccine candidate specific to Bundibugyo ebolavirus has entered production for clinical trials1. Hilleman Laboratories of Singapore, a joint venture between Merck & Co. (known as MSD outside the United States and Canada) and the Wellcome Trust, is developing it on the rVSV platform, a live vesicular stomatitis virus engineered to carry an Ebola surface protein, using a reference virus supplied by the International AIDS Vaccine Initiative (IAVI). CEPI is committing up to $8.5m, alongside a separate $30m programme improving MSD's manufacturing of the licensed Zaire-strain vaccine.
The licensed rVSV-ZEBOV vaccine, the one that ring-vaccinated its way through West Africa and eastern DR Congo, protects against Zaire ebolavirus only, and so do the two licensed antibody treatments, Inmazeb and Ebanga. Bundibugyo's surface glycoprotein, the target all three products are built around, differs enough from Zaire's that none of them cross-protects, so the candidate had to be made rather than borrowed. Uganda's 28 July declaration release states in terms that no licensed vaccine or targeted treatment exists for Bundibugyo2, a primary-source statement of the gap rather than an inference. CEPI has been buying toward it since June, when it awarded $1.9m for a fourth Bundibugyo rVSV seed stock.
Eleven weeks into the third-largest Ebola outbreak on record, Hilleman's species-matched candidate is entering trial production, after Oxford began vaccinating volunteers with its own ChAdOx1 BDBV candidate in July. Vaccine development rarely moves faster, and the honest reading of the announcement is that it protects nobody in Ituri this year: a candidate that begins production in July has no efficacy data, no regulatory dossier and no doses in the field while transmission continues. Its value is to the outbreak after this one, which for a species with three recorded outbreaks in nineteen years is a serious argument rather than a consolation.
This is a separate programme from the randomised treatment trial that began dosing patients in Ituri on 2 July, which tests remdesivir, MBP134 and obeldesivir in people already infected. A vaccine trains an uninfected immune system; those three are given to patients who already have the virus.
