New vaccine to stall African meningitis epidemics

A mother with her child, enrolled in the vaccine trial Copyright: Monique Berlier/PATH

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Trials of a new meningitis vaccine have shown it to be much more effective in boosting immunity than currently available vaccines, say researchers.

It could be available in Africa within the next two to three years, according to Dr F Marc LaForce, director of the Meningitis Vaccine Project (MVP), the group that conducted the study.

MVP announced the results of the trial last week (8 June) in Geneva.

In the trial, involving 601 children between 12–23 months old in Mali and the Gambia, a single dose of the vaccine — known as ‘meningococcal conjugate vaccine’ — produced an antibody response that was almost 20 times higher than that obtained with the older polysaccharide vaccines, reported the project researchers at the meeting.

The new vaccine was shown to be safe in this age group. The researchers expect that it will prevent infection from meningococcus strain A, and when a majority of people are vaccinated, it should protect entire populations, including unvaccinated people, in a phenomenon known as ‘herd immunity’.

Protection is expected to last for several years, reports the MVP, and will be used to prevent epidemics, rather than dispensed reactively to control outbreaks as the older vaccines are.

"This means that governments will be able to plan and finance the widespread use of the vaccine, without the fear and confusion that characterise meningitis epidemics," Simonetta Vivian, vaccine development manager of MVP, told SciDev.Net. 

The researchers expect the vaccine will initially cost 40 US cents a dose.

Further testing of the vaccine in people between the ages of 2–29 years will take place soon in India, the Gambia, Mali and at least one other African country.

This is the age group that will be mostly targeted by the mass vaccination campaigns, Vivian told SciDev.Net.

Meningococcus strain A causes explosive epidemics every eight to ten years, mainly in the African ‘meningitis belt’ that stretches from Senegal and the Gambia in the west to Ethiopia in the east.

Even with antibiotic treatment, meningitis — an infection of the membranes that surround the brain and spinal cord — kills at least ten per cent of patients and leaves up to 20 per cent with permanent problems such as mental retardation, deafness, epilepsy or limb necrosis.

The two older polysaccharide vaccines that are used against meningococcal meningitis in Africa have several weaknesses, explains Vivian.

They are ineffective in children under two years old, they cannot induce herd immunity, and they provide protection for only 2–3 years.  "This means that emergency mass-vaccination campaigns in Africa must be repeated on a regular basis — a situation that is difficult, given the economic and logistic realities of delivering public-health services in Africa," she says. 

The number of cases in Africa has been increasing, with almost 48,000 cases reported between January and 6 May this year, raising fears that a new epidemic is underway.