Pull to refresh
Logo
What Changed
Following Why Sign Up
DR Congo tests Zaire-strain Ebola vaccine against Bundibugyo outbreak

DR Congo tests Zaire-strain Ebola vaccine against Bundibugyo outbreak

New Capabilities

A 20,000-person study tests Ervebo against Bundibugyo while the WHO clears trials of two purpose-built vaccines

4 days ago: WHO approves trials of two Bundibugyo vaccines

Overview

Updated Yesterday

Congo's frontline health workers are still receiving the only Ebola vaccine available at scale, though it was designed for a different virus. The BRAVO study, which began September 19, is following 20,000 health workers in Ituri and North Kivu to see whether Ervebo protects them against Bundibugyo.

The outbreak has killed more than 5,300 people, Al Jazeera reported on November 4, and cases have appeared in Kenya and Nigeria. On November 2, the World Health Organization approved trials of two vaccines built specifically for Bundibugyo, which has no licensed shot or treatment.

Why it matters

Congo is testing a Zaire-strain shot while two Bundibugyo-specific vaccines enter trials. The results decide who gets protected.

Questions about this story

Free account needed to ask — your question is kept and asked for you right after sign-up. Answers are public.

No questions yet — be the first to ask.

Key Indicators

5,300+
Deaths
More than 5,300 as of November 2, 2026, according to Al Jazeera.
7,541
Confirmed cases (Sept 19)
The last confirmed-case total reported by DRC health authorities, as of September 19, 2026.
20,000
Frontline workers in BRAVO study
Health workers in Ituri and North Kivu provinces, the highest-risk group.
2
Bundibugyo vaccines cleared for trials
The WHO approved trials of two purpose-built vaccines on November 2, 2026.
70,000
Ervebo doses allocated to DRC
From the global Ebola vaccine stockpile, coordinated by the WHO.
2
New countries reporting cases
Kenya and Nigeria, per MSF's November 2 brief.

Voices

Curated perspectives — historical figures and your fellow readers.

Sign up to generate historical perspectives on this story.

Log in Sign Up

People Involved

Dr. Guyguy Manangama
Dr. Guyguy Manangama
Epidemiologist and deputy director of operations, MSF
Overseeing the BRAVO vaccination study

Organizations Involved

Médecins Sans Frontières and Epicentre
Médecins Sans Frontières and Epicentre
International medical humanitarian organization and its research arm
Running the BRAVO study and pressing for wider access to Ebola vaccines

MSF, with its epidemiological research center Epicentre, designed and runs the study evaluating Ervebo among frontline workers.
World Health Organization
World Health Organization
UN Agency
Approved trials of two Bundibugyo-specific vaccines on November 2, 2026, while coordinating the outbreak response

The WHO runs the training center in Bunia where vaccinations began and coordinates the global Ebola vaccine stockpile.
Merck & Co.
Merck & Co.
Pharmaceutical company
Manufacturer of the Ervebo vaccine

Merck developed Ervebo, the only Ebola vaccine available at scale, produced in Germany.

Timeline

July 2026 November 2026

6 events Latest: 4 days ago
Tap a bar to jump to that date

  1. WHO approves trials of two Bundibugyo vaccines

    Latest Public Health

    The World Health Organization cleared trials for two vaccines designed against the Bundibugyo virus, Al Jazeera reported. No vaccine is licensed for the strain.

  2. MSF warns vaccine access gaps persist

    Public Health

    MSF's access campaign published a brief on four candidates: Ervebo, rVSVΔG-BDBV-GP, ChAdOx1-BDBV-GP and mRNA-1469. It said vaccines must reach affected communities and countries without delay.

  3. Rollout reported as death toll passes 3,600

    Public Health

    Confirmed cases hit 7,541 with 3,639 deaths; WHO warns the outbreak could surpass the 2014-2016 record.

  4. BRAVO vaccination study launches in Bunia

    Public Health

    MSF and Epicentre start vaccinating 20,000 frontline workers in Ituri and North Kivu against the Bundibugyo strain.

  5. WHO records 61 health zones hit and 2,007 people vaccinated

    Public Health

    WHO Disease Outbreak News reports 6,757 confirmed cases in the DRC, cases in Uganda and France, and 2,007 people already vaccinated as of September 6.

  6. PARTNERS treatment trial begins enrolling in Ituri

    Public Health

    A clinical trial testing treatments for Bundibugyo virus disease opens at five facilities in Ituri. It has enrolled over 300 confirmed cases as of September 7.

Scenarios

1

Study shows Ervebo protects against Bundibugyo

Uncertain Resolves by Q3 2027

Discussed by: MSF epidemiologist Guyguy Manangama, who noted preliminary data suggest partial protection; Epicentre researchers

Interim or final BRAVO data show vaccinated frontline workers had significantly lower infection or severe-disease rates than unvaccinated comparison groups. That would support expanding vaccination beyond the initial 20,000 workers and give health authorities a working tool for this outbreak and future Bundibugyo events.

2

Bundibugyo-specific vaccine reaches the field

Possible Resolves by Q2 2027

Discussed by: MSF, which states several Bundibugyo-targeting vaccines are in development and may be available in coming months

A vaccine developed specifically for the Bundibugyo strain clears clinical trials or receives emergency authorization and begins rollout in the DRC. This would make the Ervebo experiment moot and give Congo a purpose-built tool, though it depends on trials moving faster than the outbreak.

3

Outbreak becomes deadliest on record

Possible Resolves by End of 2027

Discussed by: World Health Organization, which says the outbreak is on track to surpass the 2014-2016 West Africa epidemic

The outbreak continues spreading into underprepared areas amid insecurity, displacement, a health workers' strike, and intense population movement. If cumulative deaths exceed the roughly 11,300 from West Africa, it becomes the deadliest Ebola outbreak ever recorded — driven by the complete absence of a proven countermeasure for this strain.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

December 2013 - June 2016

West Africa Ebola epidemic (2014-2016)

The deadliest Ebola outbreak on record killed more than 11,000 people, mostly in Guinea, Liberia, and Sierra Leone. Caused by the Zaire strain, it drove crash-development of the vaccine that became Ervebo, tested in a 2015 ring-vaccination trial in Guinea that showed near-perfect protection.

Then

The Guinea trial gave the world its first effective Ebola vaccine and established ring vaccination as the standard response strategy.

Now

Ervebo received regulatory approval and became the default tool for every subsequent outbreak.

Why this matters now

The WHO warns the current Bundibugyo outbreak is on track to surpass this death toll — but without a proven vaccine for its strain.

August 2018 - June 2020

North Kivu Ebola outbreak (2018-2020)

The second-deadliest Ebola outbreak on record, centered in the same eastern Congo provinces now affected. Ervebo was deployed at scale in an active outbreak for the first time, vaccinating hundreds of thousands of people before the outbreak was declared over.

Then

More than 2,000 people died despite the vaccine, but mass vaccination plus community engagement ultimately contained the Zaire-strain epidemic.

Now

It became the playbook for outbreak response in the region.

Why this matters now

This is the template MSF and the WHO are following now — but the strain is different, the one variable the playbook doesn't cover.

August - December 2007

Bundibugyo outbreak, western Uganda (2007)

The Bundibugyo strain was first identified in Uganda's Bundibugyo district. The outbreak was smaller and less deadly than Zaire-strain epidemics, and it had no licensed vaccine or treatment. The strain reappeared only rarely afterward.

Then

The outbreak was contained with basic infection control, and nearly two decades passed with little research into a Bundibugyo-specific vaccine.

Now

The strain's rarity left the world unprepared for a large-scale emergence.

Why this matters now

This is Bundibugyo's first major return, and the lack of preparedness is why Congo is testing a Zaire-strain vaccine against it.

Sources

(11)
+5
Médecins Sans Frontières Doctors Without Borders - USA Medical Xpress Al Jazeera Los Angeles Times Anadolu Agency KSAT / Associated Press World Health Organization via ReliefWeb BBC News Al Jazeera Médecins Sans Frontières via ReliefWeb