The Democratic Republic of Congo has been fighting the fastest-spreading Ebola outbreak in history since May 2026. By Tuesday, 2,011 people were dead from 4,381 confirmed cases — a 46% fatality rate. The virus is Bundibugyo ebolavirus, a strain distinct from Zaire — the variety behind every major outbreak since 2014 — and one for which no approved vaccine or treatment existed when the outbreak started. WHO declared a global health emergency on May 16. The epicenter is Ituri Province in northeastern DRC, which accounts for 88% of cases and sits in an active conflict zone. WHO Regional Director Dr. Mohamed Yakub Janabi said Tuesday that officials are "chasing the virus, the virus is ahead of us."

WHO Changed Its Mind on Ervebo

Cross-protection evidence changed the calculus — WHO reversed its May ban and approved a Phase 3 trial.

Cross-protection evidence convinced WHO's advisory board. In May, WHO had formally recommended against using Ervebo — the licensed vaccine that controlled the 2018-20 Kivu outbreak — outside controlled research settings. Ervebo targets Zaire ebolavirus. WHO judged cross-protection against Bundibugyo "limited and inconclusive." Then researchers published results in The New England Journal of Medicine: in laboratory tests of serum samples, Ervebo "may offer cross-protection against the Bundibugyo virus." On July 31, WHO's vaccine advisory board reversed its May recommendation unanimously — Ervebo should go directly into a Phase 3 clinical trial. The consortium targeting mid-September for launch includes DRC's National Institute of Biomedical Research, CEPI, the Institute of Tropical Medicine in Belgium, MSF, and Africa CDC.

Ervebo already has the safety record to skip earlier trial phases. Jennifer Nuzzo, a professor of epidemiology at Brown University, called the trial "an important development" that "may be an expedient approach to lessening the severity of illness." Gavi CEO Sania Nishtar has called the outbreak "the largest in the country's history and could well become the largest outbreak ever." IAVI, Moderna, and Oxford each have a Bundibugyo-specific candidate in Phase 1 trials — but none will reach the outbreak zone for months.

But the Trial Still Can't Find the Patients

Ring vaccination requires contact tracing — and tracing has nearly collapsed in DRC.

Ring vaccination only works if you can find the contacts. Africa CDC's own data show responders are tracing roughly 10 contacts per confirmed case — versus 57 per case in the Kivu outbreak that Ervebo helped stop. Africa CDC Director-General Dr. Jean Kaseya said the contact lists "don't mean anything because it is not accurate." At MSF's main treatment center in Bunia, 90% of admitted patients had never appeared on any contact list. That means most new infections are spreading outside any monitored network — beyond the reach of ring vaccination.

Donors have left a $200 million hole in the response budget. The WHO/Africa CDC six-month plan needs $518 million; donors have pledged roughly $316 million. Health workers in Ituri have been striking over unpaid wages since mid-July. The outbreak has infected 151 health workers and killed 44. Nuzzo said "the biggest challenges are likely to be operational...making sure people at-risk...can get the vaccine in an insecure setting." Dr. Kaseya said at a July summit: "People are dying because there are no vaccines, no medicine and no funding."

And the Preparedness Gap Came First

The world built Ebola defenses around Zaire. Bundibugyo exposed what that left out.

The diagnostic tools failed before the vaccines did. Infectious disease physician Dr. Krutika Kuppalli and Congolese virologist Placide Mbala wrote in STAT News on August 10 that early molecular diagnostic assays "optimized for EBOV performed poorly when confronted with Bundibugyo virus, delaying diagnosis until updated assays could be developed." They argued the failure runs deeper: "preparedness investments remained disproportionately focused on the Ebola virus responsible for the last global crisis, leaving us less prepared for the broader range of Ebola viruses." Questions about Ervebo's cross-protection "should have been asked and answered before a crisis," they wrote.

Dismantling USAID removed the infrastructure the outbreak response depends on. Dennis Carroll, former director of USAID's Emerging Pandemic Threats program, said the USAID closure "led to the disappearance of support for infrastructure" — things like getting personnel to hospitals and moving lab samples to testing sites. Former USAID Administrator Samantha Power said: "I don't believe we would have a spiraling Ebola epidemic if USAID had not been dismantled."

Where This Lands

WHO's reversal on Ervebo is a genuine scientific development — cross-protection evidence changed what was knowable, and the advisory board responded. On the ground, the obstacle is plain: ring vaccination requires contact tracing, and DRC is tracing 10% of what worked in Kivu. Kuppalli and Mbala point to a deeper failure: the world spent a decade building defenses against Zaire, not the broader family of Ebola viruses. Bundibugyo arrived in a system never designed for it.

Sources