The Democratic Republic of Congo is set to vaccinate frontline health workers against Ebola using a vaccine whose effectiveness against the Bundibugyo strain remains unknown, as the outbreak becomes the country’s deadliest on record.
The International Coordinating Group on Vaccine Provision has allocated 70,000 doses of Ervebo to the DRC, with 50,000 doses reserved for healthcare and other frontline workers and another 20,000 for a clinical trial.
The World Health Organization says Ervebo is approved for use against the more common Ebola Zaire strain, but there is currently no evidence confirming that it can protect against the Bundibugyo strain.
WHO says early laboratory and animal studies suggest the vaccine may provide some protection, making the clinical trial important in determining whether it can be used against the current outbreak.
Placide Mbala Kingebeni, a Professor at the University of Kinshasa Medical School, says the vaccine is being deployed without established efficacy data against the Bundibugyo strain, but health authorities hope it can provide some benefit as the outbreak continues to spread. According to local authorities, the disease has killed 2,325 people, surpassing the 2,299 deaths recorded during the DRC’s 2018-2020 Ebola outbreak, which was previously the country’s deadliest.
The outbreak, declared on May 15, has also become the country’s largest in terms of confirmed cases, with 4,945 cases recorded so far. A total of 730 patients remain in isolation or hospital, while 1,040 people have recovered.
The case fatality rate has risen to 46 percent. The current outbreak is second only to the 2014-2016 West African Ebola outbreak, which recorded more than 28,000 cases and 11,000 deaths. However, health authorities say the Bundibugyo outbreak is spreading and killing people much faster. Professor Yap Boum II, who heads the Ebola response team at the Africa Centres for Disease Control and Prevention, says the vaccination intervention comes at a critical moment.
Boum says there is currently no confirmed vaccine or treatment specifically for the Bundibugyo strain, making it necessary to test available tools while gathering scientific evidence. Apart from the doses going to frontline workers, another 20,000 doses have been allocated for a Phase Three clinical trial to understand the impact of the vaccine on the Bundibugyo virus, since Ervebo is already considered safe and approved for use against the Zaire strain.
Unlike the Zaire strain, Boum says the Bundibugyo strain attacks differently, with symptoms appearing much later after infection. Because of the delayed appearance of symptoms, infected people can continue interacting with others without knowing that they have contracted the virus, making it harder for health authorities to identify contacts and break chains of transmission.
Boum says, apart from the vaccine trial, researchers are also studying two treatment options, with 200 participants already enrolled in one study and 76 in another involving a drug called obeldesivir in Bunia and Rwampara.
WHO Director-General Dr Tedros Adhanom Ghebreyesus has warned that the epidemic will continue until every chain of transmission is identified and broken. Tedros says responders are struggling to keep pace with the spread of the disease, while evidence suggests that the outbreak could have started as early as February and continued spreading silently.
“This is now the second-largest Ebola outbreak ever recorded, and it is moving faster than any previous Ebola outbreak. That’s why I call it unprecedented speed. It is being fueled by insecurity and displacement, and intense population movement along roads, rivers and mining routes,” he said.
Tedros says his biggest concern is that people are dying outside the formal response system. “They are dying at home, in their communities, outside treatment centres, and outside known contact lists,” he said. More than 160 healthcare workers have contracted Ebola, with at least 40 of them dying from the disease.
The response has also been complicated by ongoing conflict in eastern DRC involving government forces, the Rwanda-backed M23 armed group and other armed groups. The fighting has restricted access to affected communities, disrupted health services and displaced thousands of people, making contact tracing and safe burials increasingly difficult.
M23 has also announced measures aimed at limiting transmission in areas under its control, including suspending shared taxi and boat travel to and from Ebola-affected areas controlled by the government. However, the group’s involvement in the response comes amid international condemnation and sanctions over alleged atrocities against civilians.
Dr Mercy Kyeng, an epidemiologist at the Africa CDC, says another challenge is that many people continue to seek treatment from private health facilities. She says some of these facilities lack adequate infection prevention and control measures, increasing the risk of transmission to health workers and other patients.
The combination of delayed symptoms, population movement, insecurity and gaps in infection prevention and control is complicating efforts to contain the outbreak. The growing outbreak has also triggered concern in neighbouring countries, including Uganda, South Sudan and the Central African Republic.
The UN and its global health partners are working to prevent the spread of Ebola to neighbouring countries. WHO and the Africa CDC have been working with countries in the region to strengthen surveillance, laboratory testing, infection prevention and control, clinical care, community engagement and preparedness.
The UN humanitarian office, OCHA, has allocated 54.5 million dollars to accelerate the response in the DRC, prepare neighbouring countries for possible spread and strengthen community trust in the public health response. In the Central African Republic, the UN peacekeeping mission, MINUSCA, is supporting local authorities with surveillance, preparedness, communication and community awareness.
UN spokesperson Stéphane Dujarric says the mission is also providing technical and logistical assistance, including transporting health experts and delivering essential equipment and supplies. WHO spokesperson Tarik Jašarević says the agency has initiated a “major scale-up in every aspect of the response” to Ebola.
WHO has also convened cross-border consultations involving the DRC, Central African Republic, Republic of Congo, South Sudan and Uganda to strengthen disease surveillance and pandemic preparedness. The countries have agreed to strengthen cooperation in surveillance and preparedness as the risk of regional spread increases. WHO says it hopes to reverse the fast-moving spread of Ebola within three months by bringing transmission under control.
However, the agency says responders still need safe access to affected communities and additional resources to end the outbreak and save lives.
