Congo Has Started Vaccinating Against Ebola With a Vaccine Built for a Different Ebola

Twenty thousand are for a Phase 3 clinical trial designed to find out whether the vaccine does anything against this species. Fifty thousand are for frontline and health workers.

That second number is where the honest tension sits. Giving a vaccine of unproven effectiveness to the people at highest risk of exposure is defensible on the grounds that a possible partial benefit beats none, and it is the kind of decision every outbreak response eventually has to make. It is also, on any plain reading, a large deployment of a product the guidance says should not be deployed programmatically. Both of those things are true at once, and the response is being conducted in the open about it.

What is actually being tested

Whether an eleven year old vaccine has a second use nobody could confirm until an outbreak of the wrong species arrived.

That question has been open since Ervebo was licensed. It could not be answered in a laboratory, because the only way to measure effectiveness against a species is to vaccinate people who are being exposed to it. This outbreak is the circumstance in which the question gets answered, which is a bleak sentence and an accurate one.

Work on a vaccine for the right species is under way and will not arrive in time for this. The University of Oxford's Vaccine Group and Moderna have both begun human trials of Bundibugyo specific candidates, each at Phase 1, the stage that establishes safety, tolerability and immune response rather than whether it protects anyone.

The part that has nothing to do with vaccines

The outbreak is spreading through a region already carrying armed conflict, displacement, food insecurity and other health emergencies at the same time.

That is the variable that decides how this ends, and it is the one no laboratory addresses. Ebola is stopped by finding cases quickly, tracing contacts, isolating them and burying the dead safely, and every one of those depends on people being reachable and willing to be reached. A population that is moving because of violence is neither.

We made that argument when this outbreak was six weeks old, in a piece about health systems rather than pathogens, and nothing since has weakened it. For readers with travel in the region, our departure checklist covers what official guidance currently asks for.

The vaccination campaign is the visible part of this response and it is the smaller part. What the numbers say is that the invisible part is not working yet.