The outbreak has caused more than 5,600 suspected cases
A children's charity has warned that a yellow fever outbreak in the Democratic Republic of Congo (DRC) and Angola is on brink of going global.
Doctors from British-based charity Save the Children say they are battling to stop the epidemic amid a vaccine shortage.
The outbreak is already said to have killed 242 people in Angola.
Heather Kerr, Save the Children’s country director for the DRC, said: "There is no known cure for yellow fever and it could go global."
"The mass vaccination campaign in Kinshasa needs to take place now so that we can try and stop Yellow Fever spreading by land and air to more cities in Africa and across the world."
"We've got to urgently reach as many children and families as we can with the supplies that are left, and this is the only way we are able to do that right now. We can only hope this will be enough to stop the epidemic spreading any further," Kerr added.
The charity says the outbreak is the largest to hit the region for 30 years - and has "all but emptied" global emergency stocks of vaccine.
Save the Children says there are only seven million emergency vaccines available - too few to even fully cover Kinshasa, let alone the whole of the DRC.
The charity's rapid reaction Emergency Health Unit (EHU) has deployed to support the country's Ministry of Health with a mass vaccination campaign in the capital of Kinshasa.
The campaign, which begins Wednesday, is part of a last line of defence to stop the deadly virus spreading through the city of more than 10 million people.
Yellow fever is an acute viral disease transmitted by infected mosquitoes. The "yellow" in the name refers to the jaundice that affects some patients.
Symptoms include fever, headache, jaundice, muscle pain, nausea, vomiting and fatigue.
The World Health Organisation (WHO) says a small proportion of patients who contract the virus develop severe symptoms, and approximately half of those die within seven to 10 days.
While Save the Children say in this outbreak, about 20% of people who have caught yellow fever have died.
The Democratic Republic of the Congo's Ministry of Health declared an epidemic in three provinces back on June 20th.
"Concern continues to grow about the spread of the disease in Democratic Republic of the Congo, particularly in border zones and in densely populated Kinshasa, home to more than 10 million people," the WHO says.
"Kisenso, one of Kinshasa's 35 health zones, has seen a cluster of suspect and confirmed cases of yellow fever among children living in neighbouring streets."
The outbreak has caused more than 5,600 suspected cases of the deadly mosquito-borne disease.
The WHO says protection against yellow fever is possible, thanks to an existing vaccine - with more than 13 million people in Angola and more than three million in DRC having already been vaccinated.
It adds that additional funds will help provide for the planned vaccination of more than 16 million more people in the two countries.
Last month, the European Centre for Disease Prevention and Control (ECDC) said: "The outbreaks in Angola, the DRC and Uganda are significant. People in the region frequently travel by road and plane to neighbouring countries. Therefore the risk of exporting the virus to other countries is high."