The World Health Organisation (WHO) has confirmed the Democratic Republic of the Congo (DRC) will begin using a second Ebola vaccine as part of efforts to curtail the epidemic that has killed more than 2 000 people in the last 13 months.

The experimental vaccine, manufactured by the US-based firm Johnson & Johnson, will be introduced from mid-October in areas which did not have "active Ebola transmission", the UN health agency said in a statement on Monday.

"The DRC authorities, in deciding to deploy the second experimental vaccine to extend protection against this deadly virus, have once again shown leadership and their determination to end this outbreak as soon as possible," WHO Director-General Tedros Adhanom Ghebreyesus said on Monday.

The Johnson & Johnson product will complement another experimental vaccine produced by US pharmaceutical giant Merck, which has been administered to approximately 225 000 people to date.

The introduction of a second vaccine has been a source of controversy among health officials in DRC, where Ebola erupted in August 2018 in the country's eastern North Kivu and Ituri provinces.

A toxic mix of deep-rooted insecurity in the region, widespread mistrust over the outbreak and response efforts have significantly hampered the bid to halt the spread of the virus.

There have been regular attacks on medical teams trying to curtail the epidemic.

Former health minister Oly Ilunga Kalenga, who was stripped of oversight of the Ebola response in July, opposed the second vaccine's use. He said it had not been proven safe or effective and could confuse local populations already in parts mistrustful over Ebola.

On Monday, medical charity Doctors Without Borders (Medecins Sans Frontieres, or MSF) criticised the pace of ongoing inoculation, terming is "too slow".

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MSF singled out the WHO for imposing "tight controls on supply and eligibility criteria" over Merck's product and said an independent committee should be created to oversee vaccination efforts instead.

WHO's approach is centred on a so-called "ring strategy", whereby all people found to have come into contact with someone with a confirmed case of Ebola are given the vaccine.

On occasions, blanket "targeted geographic vaccination" of entire neighbourhoods deemed to be at high-risk from the virus, is also carried out rather than vaccinating only known contacts and contacts of contacts.

According to MSF, between 450 000 and 600 000 people should have been immunised by now.

"Our capacity to carry out real-time assessments and react accordingly is severely undermined by a rigid system which is hard to comprehend," Natalie Roberts, MSF's emergency coordinator, said in a statement.

"Every day we see known contacts of confirmed Ebola patients who have not received their dose despite being eligible for vaccination.

"It's like giving firefighters a bucket of water to put out a fire, but only allowing them to use one cup of water a day."

Managing the 'finite doses available'

Commenting on MSF's criticisms, WHO spokesman Tarik Jasarevic said the agency was carefully managing the "finite number of doses available".

"If all doses were sent to the DRC, there would be no reserves available to respond should cases emerge in any of the high-risk neighbouring countries," Jasarevic told Al Jazeera.

He added that an international committee, such as the one called for by MSF, could only be used to manage licensed vaccines.

Neither Merck's nor Johnson & Johnson's Ebola vaccines are licensed.

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"When the vaccine is licensed, this would be an appropriate mechanism for managing supply," Jasarevic said.

So far, more than 3,000 people have been infected by Ebola during the current outbreak in DRC.

Earlier this year, a handful of cases were confirmed in neighbouring Uganda after infected patients crossed the border.

All those affected either died or were sent back to DRC for specialised treatment.

Fears of a possible regional spread spiked again earlier this month after WHO criticised Tanzania for failing to share detailed information on suspected cases of the virus.

Overall, the epidemic is the second worst of its kind, behind a 2013-16 outbreak in West Africa that killed more than 11,300 people.

WHO was heavily criticised for its sluggish response to the crisis in West Africa, which it repeatedly declined to declare a global emergency until the virus was spreading explosively.