A vaccination campaign is due to begin in the Congo at the weekend, in response to the Ebola outbreak in the Central African country, the World Health Organisation (WHO) said.
A first batch of 400 vaccine doses arrived by helicopter in the remote affected area earlier in the day, Patrick Otim, the local head of WHO operations, said in Geneva on Friday.
A new confirmed case around 70 kilometres from the outbreak area in the Bulape region of Kasaï province is fuelling concerns about a wider spread of the often fatal disease.
Aid workers who reached the area have identified hundreds of people who were in contact with those infected and would be the first to be vaccinated.
The first cases were reported in early September.
One problem is that the vaccine must be kept at low temperatures but there is no reliable electricity supply in the region.
This is now being achieved with special cool boxes, Otim said.
Another 1,500 vaccine doses are to be flown in once a reliable cooling system is set up on site.
According to the WHO, there are now 25 confirmed cases.
Fourteen people have died, including three children under the age of five.
African health authorities has reported several dozen suspected cases.
However, as this number changes hourly following laboratory analyses, the WHO only reports confirmed cases.
Transmitted through physical contact and contact with body fluids, Ebola is a contagious and life-threatening infectious disease that causes fever, vomiting, bleeding and diarrhoea.
The mortality rate is extremely high if infected individuals are not treated immediately.
In 2014 and 2015, more than 11,000 people died in an outbreak in West Africa.
