The 16,250 doses of the Ervebo vaccine arrived in Kinshasa, the capital of the DRC, late on Friday evening, marking the first shipment of 70,000 doses pledged by the World Health Organization (WHO) and its partners on Thursday. More doses are expected to arrive in the coming week.

Vaccine Approved for Zaire Strain, Not Current Outbreak Strain

Although the Ervebo vaccine is approved against the Zaire strain of the virus, the Bundibugyo strain currently circulating in the DRC has no approved vaccine or treatment. Early data from animal trials, according to the WHO, suggests the Ervebo vaccine may offer some protection against the Bundibugyo strain.

Previous Use of Ervebo in Outbreaks

Samuel Roger Kamba, the DRC’s health minister, told reporters that the Ervebo vaccine had been used several times in the past, including “on a very large scale” during the 2018 to 2020 Ebola outbreak. Of the 70,000 doses intended for the DRC, 20,000 will be part of a late-stage clinical trial to test its effect on the Bundibugyo strain, the WHO said. The remaining 50,000 doses are allocated for front-line and health workers.

Deadliest Outbreak in DRC’s History

The current outbreak has killed more than 2,500 people out of nearly 5,300 confirmed cases, according to the United Nations, which warned this week that infections continue to spread “exponentially.” The outbreak was officially declared in mid-May, but it is believed to have started weeks prior. Data from the Africa Centres for Disease Control and Prevention indicates that transmission has not yet peaked and could reach three times its known rate.

Efforts to contain the virus have been hindered by ongoing armed conflict, delays in identifying cases, and a lack of infrastructure in eastern DRC, according to experts. The DRC has faced multiple Ebola outbreaks in recent years, with this latest one being the most severe in the country’s history.