KAMPALA, Uganda--The Democratic Republic of the Congo on Monday approved the use of a new experimental Ebola vaccine, nearly three weeks after health officials announced the latest outbreak of the deadly virus along the country's northeastern border.

The approval was granted by Congo's health ministry, spokesman Simba Kai said. The ministry must now decide whether to use the vaccine, which was developed by Merck & Co.

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The ministry, the World Health Organization and the medical aid organization Doctors Without Borders were discussing plans for the vaccine, Mr. Kai said. A spokeswoman for Merck said the company "stands ready to ship vaccine, if and when" Congo decides to use it.

There have been only two confirmed cases of Ebola in the latest flare-up, and at least three more who likely had it. It isn't clear if the virus is still spreading. While some 52 cases have been registered, most have been designated as potential cases and are under investigation.

Experts from the WHO say the delays in Congo's approval of the vaccine have been an impediment in efforts to contain the latest eruption of the disease, which was confirmed May 12.

The current outbreak in Congo is the first since 2014-16, when at least 28,600 people were infected in West Africa, including 11,310 who died--by far the largest Ebola outbreak in history.

Reports in the aftermath of that epidemic called for major overhauls in global health financing and in the WHO, which took on most of the blame for a delayed response that allowed the disease to spiral out of control. Since then, it has established new guidelines and procedures for responding to reports of telltale symptoms of the disease.

Monday's announcement that the vaccine had been approved for use in Congo came after Congolese experts finished a review of the protocol for using the vaccine, Mr. Kai said.

Merck announced earlier this month that it was ready to release the vaccine but because the serum isn't yet licensed, it can only be administered under a clinical study, which must be approved by government. The company has agreed with the international vaccine alliance GAVI to ship doses of the vaccine to the location of the latest outbreak.

The development of an Ebola vaccine is a significant breakthrough, especially for Congo, which has been afflicted by more outbreaks of the disease than any other nation in the world. The latest isn't far from the Ebola River, after which the virus was named in 1976.

But Congo is sub-Saharan Africa's most sprawling country, and any vaccination campaign will be complicated by the remoteness of the current outbreak, centered in Likati, about 800 miles northeast of the capital Kinshasa.

There are no road or rail links between Likati and Kisangani, the nearest city. Health officials are relying on motorbikes to reach the forested region, near Congo's border with the Central African Republic.

To be effective, the anti-Ebola vaccine must be stored in special containers at a temperature of minus 80 degrees Celsius. Equipment to safely ship and store the vaccine has arrived in Congo from Guinea, where trials of the vaccine during the large outbreak in 2015 were effective, said the WHO spokesman in Congo, Eugene Kabambi.

Write to Nicholas Bariyo at nicholas.bariyo@wsj.com

(END) Dow Jones Newswires

May 29, 2017 12:40 ET (16:40 GMT)