KINSHASA — The first 16,250 doses of the Ervebo Ebola vaccine arrived in the Democratic Republic of the Congo's capital late Friday, the opening shipment of 70,000 that the World Health Organization and partners pledged Thursday to send as the country battles its deadliest-ever outbreak of the virus.

The rollout will be split. About 50,000 doses will be administered to front-line health workers, the WHO said, and 20,000 will be used in a clinical trial to determine whether Ervebo — approved for the Zaire strain of Ebola — offers meaningful protection against the Bundibugyo strain now circulating in eastern DR Congo. No approved vaccine or treatment exists for Bundibugyo, though the WHO said early animal-trial data suggest Ervebo may offer some cross-protection.

The doses land as the WHO warned the epidemic is "growing exponentially" across the country's north and east, over an area larger than France. Close to 2,500 people have died in the outbreak, which was declared three months ago and which The James St. Journal reported earlier this week had already become the deadliest in DR Congo's history. Julien Harneis, the WHO's Ebola coordinator, said half of those deaths occurred in the last 20 days.

"It is growing faster and wider than the Ebola response," Harneis said, according to Agence France-Presse.

A rare strain

Bundibugyo is among the rarer Ebola species, with only two known prior outbreaks. Health teams in DR Congo have said they suspect the virus began circulating as early as February but that initial cases were misdiagnosed as typhoid and malaria. Conflict in the east, distrust of health authorities and traditional burial practices have slowed the response. Save the Children said in a new report that at least 180 Congolese children have lost both parents or caregivers since the outbreak began. Only the 2014-2016 West Africa epidemic, which killed more than 11,000 people, has been deadlier.

The rebels' cordon

The M23 rebel alliance, which controls parts of North Kivu and captured Goma and Bukavu in early 2025, announced its own movement restrictions on Friday. Shared taxis and passenger boats between government- and rebel-held areas of the province will be suspended for one month starting Saturday, after two travelers tested positive for Ebola in a village under M23 control. Other transport will continue under health controls. The rebel authorities had declared their zones Ebola-free in late June.

Neither the BBC nor Al Jazeera reported a start date for the Bundibugyo trial or a timetable for pushing the 50,000 front-line doses through conflict-hit territory. Congolese government or Merck commentary on the rollout's pace was absent from the reporting reviewed today.

More Ervebo doses are set to arrive next week.