Africa hit by Ebola strain with 50% fatality rate and no vaccine — CEPI steps in

A strain of Ebola virus with no vaccine, no treatment and no approved medical countermeasure is sweeping across Africa. With the suspected death toll surpassing 220, the World Health Organization has issued its highest-level international health alert.

In response, the Coalition for Epidemic Preparedness Innovations (CEPI), the international body dedicated to developing vaccines against infectious diseases, announced Monday that it had launched emergency development of three vaccine candidates.

CEPI said June 1 it would urgently accelerate development of three experimental vaccine candidates targeting the Bundibugyo Ebola virus.

The three candidates are being developed separately by IAVI, Moderna and the University of Oxford, each using a different vaccine technology platform.

CEPI will commit up to $50 million to Moderna to support preclinical and Phase 1 clinical trials, and will also fund parallel manufacturing so that Phase 2 and 3 trials can begin immediately once Phase 1 data are available. Moderna's candidate draws on the mRNA technology proven during the COVID-19 response.

Up to $3.2 million will go to IAVI to support master virus seed generation for a vaccine built on the rVSV platform — the same platform underlying approved vaccines against the Zaire strain of Ebola. The University of Oxford will receive up to $8.6 million to support preclinical work and Phase 1 preparation for a vaccine based on the ChAdOx1 platform, which underpinned the Oxford-AstraZeneca COVID-19 vaccine. The Serum Institute of India will handle clinical-grade manufacturing.

"With Bundibugyo spreading rapidly and no licensed vaccine available, every day counts," CEPI Chief Executive Richard Hatchett said. "We will work to advance these three promising candidates into safe and effective vaccines that can help bring this outbreak under control."

Ebola is not a single virus. It comprises five species: Zaire, Sudan, Bundibugyo, Taï Forest and Reston. The Bundibugyo strain carries a fatality rate of up to 50% — lower than the Zaire strain's roughly 60 to 90 percent, but still highly lethal.

The most pressing problem is the absence of any countermeasure. Licensed vaccines and antibody treatments exist for the Zaire strain, but for Bundibugyo there is no approved vaccine, no targeted treatment and not even a late-stage candidate in development. Clinicians are left with little beyond isolating suspected patients and managing symptoms.

The incubation period runs from two to 21 days. Early symptoms include fever, headache and muscle pain, followed by vomiting, diarrhea and bleeding. The virus spreads through contact with bodily fluids, blood or infected remains — not through the air, meaning casual contact alone does not transmit it. Even so, active armed conflict in the region, deep distrust of the health system and a contact-tracing rate of just 20 percent have been identified as the key factors driving the outbreak's rapid spread.

The outbreak traces back to the death of a man in the Mongbwalu area of Ituri Province in the Democratic Republic of Congo on May 5. As his body was transported home to Bunia for burial, family members and villagers who took part in funeral rites began reporting fever and bleeding.

Eight of 13 samples collected by WHO field teams tested positive, and genetic analysis confirmed the strain as Bundibugyo — not the Zaire strain that has historically dominated outbreaks.

The situation has deteriorated rapidly. WHO puts the suspected death toll at 220, with 101 confirmed cases and nearly 900 suspected cases. That compares with 105 suspected deaths just one week earlier — more than doubling in seven days. The virus has spread across 11 health zones in three eastern DRC provinces, and more than 2,200 contacts have been identified. Seven confirmed cases, including health workers, have also been reported in neighboring Uganda.

WHO Director-General Tedros Adhanom Ghebreyesus told an African Union online meeting May 25 that cases were being detected late, leaving response authorities scrambling to catch up, and warned that the trajectory was likely to worsen. WHO has classified the outbreak as the third-largest filovirus epidemic in history and declared a Public Health Emergency of International Concern (PHEIC) on May 17.

South Korea's Korea Disease Control and Prevention Agency (KDCA) convened an emergency risk assessment meeting on May 17, immediately after WHO declared the PHEIC, and raised the domestic crisis alert to the "Caution" level. The agency assessed the risk of the virus entering South Korea as low, but said it would maintain a thorough state of readiness given the disease's transmission through bodily fluids and blood.

The KDCA designated the DRC, Uganda and South Sudan as priority quarantine management zones and began conducting full gate-level screening of all arrivals from those countries. The agency also said it has established a diagnostic system capable of rapidly confirming Bundibugyo Ebola virus infection using real-time RT-PCR testing.

KDCA Commissioner Lim Seung-kwan said the agency would closely monitor the overseas situation while strengthening domestic surveillance, laboratory analysis, infection prevention and outbreak preparedness, and would work in close coordination with international health organizations. He urged anyone who has visited or returned from the affected countries to monitor their health carefully for 21 days after arrival and to report immediately to the 1339 hotline or a local public health center if they develop symptoms such as fever or abdominal pain.