New vaccine to eradicate meningitis

Outbreaks of meningitis can quickly reach epidemic proportions across a number of African countries, afflicting tens of thousands of people. Now a new vaccine appears capable of completely eradicating the disease.

"The vaccine results are exceeding all our expectations," says Dominique Caugant, Chief Scientist at the Norwegian Institute of Public Health.

Dominique headed the Norwegian segment of the international Meningitis Vaccine Project, a partnership between the World Health Organization (WHO) and the international non-profit organisation PATH.

The project's objective was to eliminate the meningitis epidemics caused by serogroup-A meningococci bacteria in the high-risk meningitis belt: the African countries south of the Sahara Desert, from Senegal in the west to Ethiopia in the east.

The result is a new and improved vaccine, MenAfriVac, which costs no more than USD 0.50 per dose.

One in ten lives lost

PATH's Marc LaForce, Director of the vaccine project, presented its preliminary results together with Professor Caugant at the conference Contributions to Global Health Research, Capacity Building and Governance, held in Oslo in September.

"The official launch of the vaccine in December 2010 was a great day for all of us on the team," recalls Dr LaForce. "Most people who work in public health never get to experience taking part in the development phase and then actually seeing a product introduced on a nationwide scale."

Globally, the WHO calculates that roughly half a million cases of meningococcal disease occur annually.  Roughly one in ten infected persons die from the disease; those who survive it are often left debilitated.

"Existing vaccines have not been good enough to prevent the occurrence of large-scale epidemics in Africa," explains Professor Caugant. "There are improved vaccines available but they are far too expensive for African countries."

Virtually no incidences

Burkina Faso was the first country to receive the new vaccine. In the course of a few weeks, everyone from the age of one to 29 was vaccinated - nearly 12 million people.

The number of people who contract the serogroup-A meningococcal disease varies from year to year, but according to Professor Caugant, 1 000 cases in the course of a week is not unusual for Burkina Faso, and up to 8 000 cases have been reported in a single week.

"Six months after the successful introduction of the vaccine," she says, "only four cases of the serogroup-A meningococcal disease had been reported - all of them unvaccinated individuals."

The primary funder of the vaccine project was the Bill & Melinda Gates Foundation. The Research Council of Norway's Programme for Global Health and Vaccination Research (GLOBVAC) provided funding for the project's Norwegian component.

The Norwegian Institute of Public Health contributed expertise in microbiology and serology in connection with the vaccine, and it is now hosting one of the studies evaluating the efficacy of the vaccine distributed in Burkina Faso.

The vaccine is also being used in mass vaccinations in Mali and Niger.

Transmitted by healthy carriers

The Norwegian Institute of Public Health is also carrying out a transmission study in Burkina Faso to determine whether mass vaccination with MenAfriVac also reduces the number of healthy carriers of serogroup-A meningococci bacteria.

At any given time, many people have meningococci in their throat without becoming ill; these healthy carriers are the main source of the spread of the bacteria.

A local team of roughly 50 workers has collected more than 40 000 throat swab samples in Burkina Faso. The first samples were taken before the mass vaccination, and the last ones will be collected in October/November 2011.

Samples are being taken from three different parts of the country and at various seasons of the year to account for natural variations.

Community immunity

"Positive samples are sent to the NIPH for further analysis," says Professor Caugant. "Preliminary results suggest that there have been substantially fewer serogroup-A carriers after the vaccination campaign, meaning the vaccine provides what is called herd immunity."

The concept of herd immunity is that the unvaccinated parts of a population are indirectly protected, since fewer carriers means reduced pressure of infection.

"This is extremely important information for other countries considering introducing the vaccine," adds Professor Caugant.

She is a proponent of establishing a child vaccination programme to ensure that the region's future young children also have immunity.


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
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