The worst yellow fever outbreak in decades, which has killed 325 people in Angola and spread as far as China, has prompted the World Health Organization (WHO) to draw up plans to eke out vaccine supplies by using one-fifth of the normal dose.
Alejandro Costa, team leader for emergency vaccination and stockpiles, said an expert meeting would consider the plan next week, paving the way for the WHO to advise countries to shift to the lower dose on a emergency basis if necessary.
Fears of a wider outbreak of the mosquito-borne disease were fuelled this week by the confirmation of locally transmitted yellow fever in Kinshasa, capital of the Democratic Republic of Congo (DRC).
A major outbreak in the city would leave healthcare authorities with little choice but to cut the dose per patient.
“If we have to vaccinate Kinshasa, that would be a trigger,” Costa said in a telephone interview on Thursday. “We don’t have enough vaccine. Kinshasa has a population of 12 million to 14 million people and we only have today around six million doses.”
Concerns about limited vaccine supplies have been building for some time, with independent medics calling for low-dose use in an article The Lancet journal in April.
Limited scientific research suggests a one-fifth dose works as well as the full dose, although it is not clear if it lasts as long. Studies to date have also only involved adults, so it is uncertain how well children would be protected.
The current outbreak of yellow fever was first detected in Angola in late December 2015 and has since spread into DRC, Congo-Brazzaville, Kenya and Sao Tome, as well as to China, which has close commercial ties with oil-rich Angola.
The International Federation of Red Cross and Red Crescent Societies called on Wednesday for an immediate scale-up in response, warning that limited vaccine supplies and other problems could turn Angola’s epidemic into a larger crisis.
While the population in the Angolan capital of Luanda is now almost completely vaccinated, this has depleted the world’s emergency stockpile of vaccines, and a slow vaccination campaign has allowed the virus to spread elsewhere.
Yellow fever is transmitted by the same mosquitoes that spread the Zika and dengue viruses, although it is a much more serious disease. The “yellow” in the name refers to the jaundice that affects some patients.
Although approximately six million vaccine doses are kept in reserve for emergencies, there is no quick way to boost production when there is a spike in demand, as at present.
Manufacturers, including the Institut Pasteur, government factories in Brazil and Russia, and French drugmaker Sanofi, use a time-consuming method involving sterile chicken eggs.
(Reporting by Ben Hirschler; Editing by Gareth Jones)