More than 6,000 suspected cases and 443 deaths from meningitis have been recorded in Niger in the past three months. But a shortage of vaccines has hindered timely implementation of a vaccination campaign.
Dr. Pauline Lechevalier, a Médecins Sans Frontières (MSF) vaccination specialist, discusses recent advances in responding to meningitis epidemics, and reflects on the improvements that are still needed.
Three months after the beginning of the meningitis epidemic in Niger, there are still difficulties with implementing a vaccination campaign. Why?
The World Health Organization (WHO) recommends that vaccination campaigns be implemented in response to epidemics. The threshold for declaration of an epidemic is when there are ten cases per 100,000 population recorded in one week. The first districts in Niger affected by the epidemic crossed this threshold in mid-February. Since then, the vaccination response was limited to Niamey and two districts of the Dosso region, involving a total of about 500,000 doses of vaccine. By May 15, 11 other health districts had reached the epidemic threshold, but the vaccination campaign didn't reach them.
There are several reasons for the delay in the response to vaccinate. Firstly, the magnitude of the epidemic took everyone by surprise because since introduction of the meningococcal A vaccine in 2010, Niger had been free of epidemics of similar scale. Thus the international provisioning mechanism for vaccines was not prepared to respond to such an epidemic, which explains some of the initial delay. Meanwhile the global emergency stockpile of vaccines had been exhausted in late April, largely the result of another epidemic in Nigeria and the cancelled delivery by one of the vaccine producers. It therefore became urgent to find alternative sources for hundreds of thousands of additional doses of the vaccine. These are now expected to be available in the coming days.
It was thought that the problem of meningitis had been resolved with the development of a new vaccine. Can you tell us about this vaccine?
The MenAfriVac vaccine, which has been introduced progressively across Sub-Saharan Africa since 2010, has so far been administered to over 200 million people in the 'meningitis belt', which runs from Senegal to Ethiopia. It is very effective against meningitis due to the meningococcal A strain, or serogroup. A study in Chad in 2012, for example, showed a decrease of 94 per cent in meningitis A cases in three regions where the vaccine was introduced. In addition, this conjugate vaccine reduced nasopharyngeal carriage, in other words the person-to-person transmission of the disease, by 98 per cent.
MenAfriVac’s introduction has helped to stop the cycle of deadly meningococcal A epidemics in the region, but smaller-scale outbreaks caused by other strains—particularly the W135 and C strains—continue to be recorded. The current epidemic in Niger, which is an extension of the epidemic in neighbouring Nigeria, is the first large meningococcal C epidemic ever recorded in the country.
What vaccines can be used against meningitis?
To vaccinate against meningococcal C disease, there are polysaccharide vaccines which can cover several serogroups in combination (notably A/C, A/C/W135 and A/C/W135/Y). Unfortunately, they only offer protection for a period of three years. Moreover, they are not recommended for children under two years old.
There are also conjugate vaccines that protect against serogroups A, C, W135 and Y, which offer protection for at least ten years, are effective in young children, and also reduce the nasopharyngeal carriage (or transmission). But the high cost of this vaccine—22 euros per dose—means that it is too expensive for use in large-scale campaigns.
Can you describe the global provisioning system for meningitis vaccines?
A global vaccine provision and inventory system was established in 1997 after the largest-ever recorded meningitis epidemic caused 250,000 cases and 25,000 deaths in West Africa in 1995-1996. The International Coordination Group on Vaccine Provision (ICG), composed of representatives of WHO, the International Federation of the Red Cross, UNICEF and Médecins Sans Frontières, is in charge of ensuring the availability and efficient use of vaccines in response to meningitis epidemics. As such it is a mechanism designed to manage shortages: ICG representatives decide on the allocation of vaccines based on an assessment of priorities and epidemiological data from the affected areas. This arbitration role is essential during an epidemic, as there may be significant pressures placed on local health authorities. This year, the ICG had expected to have 1.5 million doses of meningitis vaccine in stock, but only 800,000 doses were actually available at the beginning of the year. Of these 310,000 were used in Nigeria.
How can we prevent further epidemics of this type in the future?
Vaccination is only one element necessary for the prevention and control of epidemics. The other elements are: early detection and confirmation of suspected cases; prompt gathering and sharing of information; and adequate management of confirmed cases. For now, we are still far from being able to vaccinate people against all strains of the disease. Whether in response to epidemics, or when implementing preventive campaigns, we need conjugate vaccines against serogroups A, C, W135 and Y that are affordable and available in sufficient quantities.
The MenAfriVac vaccine experience is a good model to follow in the future. This conjugate vaccine was designed and developed for use in Sub-Saharan Africa, and gives long protection against meningococcal A. It also protects young children, can be kept outside of a cold chain, and costs only 50 euro cents.
What is Médecins Sans Frontières’ response to the epidemic?
In late April, we vaccinated about 70,000 people aged two to 15 years in two districts of the Dosso region, about 200 km east of Niamey, using the A/C/W135 polysaccharide vaccine. Since we are currently unable to vaccinate more widely, we are strengthening our support to health centres to manage those who are already sick: 3 800 people were treated in MSF-supported centres. If the extra doses of vaccines arrive quickly, we will evaluate the possibility of helping the authorities vaccinate in other districts, prioritising the most-affected areas.