Ebola Vaccine Trial Starts in Congo as Toll Hits 4,687, While Nigeria Case's Origin Stays Disputed

Since Congo declared the Bundibugyo Ebola outbreak on May 15, the virus has reached Uganda, Kenya, France and Nigeria. Today, Oct. 23, the response saw its first large-scale vaccine test, and a fight over how Nigeria's patient got infected.

Tumaini trial vaccinates first participants in Bunia

The first participants were vaccinated today in Bunia, the capital of Ituri Province, in a Phase 2/3 trial called Tumaini, Swahili for "hope." The Coalition for Epidemic Preparedness Innovations is funding and supporting it. WHO Director-General Tedros Ghebreyesus announced the start on X, calling it a DRC-led effort and writing, "Science gives us hope."

No vaccine is approved against the Bundibugyo species. The first candidate is Ervebo, which is licensed for the Zaire species of Ebola. Its effectiveness against Bundibugyo in humans has not been established.

Two vaccines built specifically for Bundibugyo are expected to join "shortly," according to the trial's backers. One is from Moderna. The other is from the University of Oxford with the Serum Institute of India.

The design is adaptive, so several candidates can be tested inside one study. It uses ring vaccination, which targets contacts of confirmed cases and other high-risk people.

"The launch of the Tumaini trial marks a critical step towards establishing whether candidate vaccines can effectively protect people against the Bundibugyo virus," said Chikwe Ihekweazu, executive director of the WHO's Health Emergencies Program.

A separate prevention study has been running since July. The EBO-PEP trial, coordinated by the nonprofit ALIMA, tests Gilead's experimental antiviral pill obeldesivir after suspected exposure. More than 250 people have enrolled out of a target of nearly 1,000. Half of those will receive a placebo.

Toll climbs past 4,680

DRC health authorities released figures late Wednesday, Oct. 21, showing 9,704 confirmed cases and 4,687 deaths as of Oct. 20. That is a case fatality rate of 48.3 percent. Africa CDC puts the death toll at about 4,700.

The WHO calls it the largest and deadliest Ebola outbreak ever recorded in Congo. It is the second-largest anywhere, after the 2014-2016 West Africa epidemic.

Around six in 10 deaths have happened outside health centers, according to UN figures. That points to continued community transmission. The latest province to confirm infections is Nord Ubangi, which borders the Central African Republic, where armed violence keeps uprooting people.

Nigeria patient's travel history contested

Nigeria confirmed its case on Oct. 20 in a woman living in Abuja who had recently been in Uganda. Health Minister Muhammad Ali Pate said she is isolated and receiving care. Authorities have identified 44 possible contacts. Nigerian officials say her symptoms began Oct. 7.

The Swiss Federal Department of Foreign Affairs said today that the woman, the Ugandan-born wife of a Swiss diplomat in Abuja, did not travel to Congo with her husband. That contradicts earlier claims about her movements.

Uganda's government spokesperson, Alan Kasujja, said Thursday that Uganda has no Ebola cases and that the government would announce any new infections. Uganda officially declared its own outbreak over at the end of August, after 20 confirmed cases and two deaths.

The WHO and Africa CDC have both said they have no confirmed information that she went to Congo.

"The source of exposure is still not known and the travel history of the patient is being pieced together now," said Dr. Patrick Otim of the WHO's emergency response programme. He added that investigators will need that information before they can say whether any onward transmission is happening.

Genetic sequencing is underway to confirm the infection is the same Bundibugyo strain circulating in Congo. Otim said infection-control measures have been pushed to private and public facilities across Abuja to limit spread inside hospitals.

Kenya's contact tracing

Kenya has reported nine cases, including one death earlier this month. The patient was a Kenyan national who had worked in Congo and flew home via Entebbe. Dr. Patrick Amoth, director general of Kenya's Ministry of Health, said all 135 contacts of the deceased patient were traced and accounted for.

What comes next

Africa CDC has scheduled an extraordinary virtual meeting for Oct. 28 to discuss the spreading outbreak. Sequencing results from Nigeria are still pending. They should show whether the Abuja case matches the Congo strain, and the exposure question remains unanswered until then. Tumaini's early efficacy data will take longer. Dr. Otim said there is still no preliminary data on whether Ervebo protects against Bundibugyo.