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A new vaccine vanquishes meningitis A in Africa

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Science  12 Sep 2014:
Vol. 345, Issue 6202, pp. 1265
DOI: 10.1126/science.345.6202.1265

The first vaccine developed specifically for Africa is an unqualified success.

Across Africa's meningitis belt, people have lined up for MenAfriVac.

PHOTO: © MONIQUE BERLIER/PATH

For more than a century, the Neisseria meningitidis bacterium has swept across large swaths of Africa every few years. Striking during the dry season, it causes meningitis that kills 5% to 10% of those infected and leaves many others deaf or disabled. Although effective—and expensive—vaccines exist against the meningitis strains that plague Europe and the United States, no good one was available to protect Africans against serotype A, the most common strain in Africa. That has changed—and the result, says Brian Greenwood, an epidemiologist at the London School of Hygiene & Tropical Medicine, is “probably the most dramatic success I have ever seen.”

In 2000, the World Health Organization convened global health experts who came up with an idea: Make a safe and effective vaccine specifically for Africa for an African price. And make it fast. With $70 million from the Bill & Melinda Gates Foundation, the Meningitis Vaccine Project, a public-private partnership headed by infectious disease specialist Marc LaForce, got started. The basics were agreed upon quickly: To induce long-lasting immunity, the vaccine would have to be a conjugate, a meningococcus A polysaccharide joined to a tetanus protein to elicit a stronger immune response. And it would have to cost less than 50 cents a dose, a price the Serum Institute of India Ltd. agreed to deliver even before development began.

MenAfriVac is that vaccine. By 2009, trials in Senegal, Mali, and other countries had shown the vaccine to be safe and effective, and in December 2010, Burkina Faso, at the time the hardest hit country in Africa's meningitis belt, became the first to roll out the vaccine. Within just 10 days, about 70% of the target population—anyone between 1 and 29 years old—had received it. No cases of meningitis A were recorded the next year. In Chad, three regions introduced the vaccine in December 2011 in the midst of an epidemic; during the first half of the following year, those regions recorded just 57 cases of meningitis, none of them caused by N. meningitidis A, Greenwood and his colleagues reported in January in The Lancet. Across the rest of the country, the case number was 18 times higher, 44 per 100,000. “In every single country where the vaccine has been introduced, group A Neisseria meningitis disease has fallen to zero,” LaForce says.

What made it such a success? For one, people in West Africa desperately want the vaccine—almost every family there knows the devastating impact of meningitis firsthand, says Seth Berkley, who heads GAVI, the Vaccine Alliance, which has budgeted $370 million to introduce the vaccine across the continent. Another reason: Unlike earlier vaccines, MenAfriVac also gets rid of the bacterium in asymptomatic people, further increasing herd immunity. By the end of this year, Berkley estimates 200 million people will be vaccinated, with the remaining 100 million slated for 2015.

How long the vaccine's protection will last is still unclear, however, and scientists worry that other strains of the bacterium could take over the continent. Meanwhile, the Serum Institute of India has already set its sights on the next goal: an affordable vaccine that will protect against meningitis strains C, Y, W, and X as well. LaForce says that vaccine will enter field trials in 2015.

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