Yellow Fever Outbreak in Africa Strains World Vaccine Stocks

  • Disease is suspected to have spread from Angola outbreak
  • Emergency vaccination stockpile has been depleted twice

An outbreak of Yellow fever that began in Angola and spread to the Democratic Republic of Congo risks draining global stocks of the vaccine needed to prevent infections with the virus, which can lead to jaundice, abdominal pains and death, from spreading.

At least 3,294 suspected cases have been reported in Angola since December, of which 861 have been confirmed through laboratory tests, according to the World Health Organization. Congolese Public Health Minister Felix Kabange Numbi said Monday that 67 cases of the disease have been confirmed in his country, of which all but three are suspected to be linked to the outbreak in neighboring Angola.

Vaccination programs have already begun, but global stockpiles are limited, according to the WHO. About 6.8 million vaccines were available as of June 17, with more than 12 million doses already used this year in Angola alone. The vaccine is made using sterile chicken eggs over 12 months, a period that limits the ability of the four major manufacturers to ramp up production.

Symptoms of Yellow fever include fever, muscle pain, nausea and vomiting. Around 15 percent of patients enter a second more toxic phase marked by jaundice, abdominal pain and bleeding from the mouth, nose, eyes or stomach, half of whom die within 14 days. In the current outbreak, 347 people are suspected or have been confirmed to have died from the virus in Angola and 75 in Congo, according to the WHO.

Across Borders

The disease is transmitted by mosquitoes, although infected people can carry the virus across borders. The disease can only spread further if that country has a mosquito species able to transmit the virus. Two cases of Yellow fever in Kenya and 11 more in China have also been confirmed as infections imported from Angola, the WHO said in a June 23 situation report.

About 90 million vaccines are normally produced a year, the majority of which are used in regular vaccination programs. Six million doses are reserved for an emergency stockpile, which was depleted for the first time ever earlier in 2016 and has since been exhausted again. French drug-maker Sanofi shipped 11 million doses to Africa between January and June and will send more vaccines as soon as possible, company spokeswoman Julia Jara said last week by e-mail.

In Congo, more than 2 million people have been vaccinated since May 24, although millions more require the shot. The WHO is in the process of shipping a further 1.3 million doses of the vaccine to inoculate people in the capital, Kinshasa, and the provinces of Kongo Central and Kwanga, Eugene Kabambi, a WHO spokesman, said by phone from the western city of Matadi. As many as 5 million doses are still required for those at risk, he said.

Mass Vaccination

Congo’s health minister said Monday that the government would begin a mass vaccination program in July, using a fifth of the normal doses to provide protection for at least 12 months against the disease. The reduced dose will be used to vaccinate 11.6 million people in Congo’s capital and along the border with Angola, Numbi said. He didn’t confirm how many vaccines Congo expects to receive.

Kinshasa, a city of 12 million people, has decrepit infrastructure and inadequate health facilities. Experts are concerned that an outbreak there and in other cities would quickly deplete global stockpiles.

“The worst case scenario is to have several cities affected simultaneously,” William Perea, coordinator of the Control of Epidemic Diseases department at the WHO, said in an e-mailed response to questions. “That will require mass vaccination of tens of millions of people at the same time, which will exceed by far vaccine supply.”


MAP: Democratic Republic of Congo
MAP: Democratic Republic of Congo

Aid organizations such as the International Federation of Red Cross and Red Crescent Societies say current data could underestimate the extent of the outbreak and that, although the global response has improved, more resources are required.

“The surveillance of Yellow fever is quite difficult so current numbers are probably heavily underestimated,” Amanda McClelland, a senior officer with the IFRC, said by phone from Luanda, Angola’s capital.

Since symptoms are hard to detect and often appear only two weeks after a patient has been bitten, data on Yellow fever outbreaks normally lags the reality by three to four weeks, according to McClelland.

“There has been an improvement in the national and international response in the last month but whether that is sufficient to control the epidemic we will have to wait and see,” she said.

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