A Case-control Study of the Efficacy of a New Serogroup A Meningococcal Conjugate Vaccine (MenAfriVac) in Mali and Niger
A Case-control Study of the Efficacy of a New Serogroup A Meningococcal Conjugate Vaccine (MenAfriVac) in Mali and Niger
Major epidemics of meningococcal meningitis occur in countries of the African Sahel and
 sub-Sahel every few years. Most of these epidemics are caused by meningococci belonging to
 serogroup A. Until recently there has been no serogroup A conjugate vaccine available to
 prevent epidemics in Africa because none of the major pharmaceutical companies wanted to
 develop such a vaccine for commercial reasons. For this reason a public private partnership
 was established in 2001, the Meningitis Vaccine Project (MVP), with support from the Bill and
 Melinda Gates Foundation, to develop an affordable new serogroup A meningococcal conjugate
 vaccine for Africa. The new vaccine, MenAfriVac™, received WHO pre-qualification in 2010 and
 mass campaigns started in Burkina Faso, Mali and Niger in 2010. It is expected that full
 coverage through mass vaccination campaigns will be achieved by the end of 2011 in these
 three countries. A case-control study will be conducted in Mali and Niger during the epidemic
 seasons of 2012 and 2013 to assess the efficacy of MenAfriVac™.
Massive epidemics of meningococcal disease continue to occur every few years in countries of
 the African Sahel and sub-Sahel - the African meningitis belt. In 2009 there were more than
 50,000 reported cases in Nigeria alone. Most of these epidemics are caused by meningococci
 belonging to capsular polysaccharide serogroup A. African epidemics can be contained by
 existing meningococcal polysaccharide vaccines, saving many lives, but epidemics are not
 prevented by use of these vaccines. Recently, a new serogroup A meningococcal
 polysaccharide/protein conjugate vaccine (MenAfriVac), which may be able to prevent
 epidemics, was prequalified by the World Health Organization. This vaccine was developed by
 the Meningitis Vaccine Project (MVP) and is being produced at a cost ($0.40 per dose) that is
 affordable by countries of the African meningitis belt. Mass vaccination campaigns started in
 Burkina Faso, Mali and Niger at the end of 2010. Full coverage will be achieved in 2011 with
 progressive deployment to other countries in the meningitis belt.

 The safety and immunogenicity of MenAfriVac have been established through phase 1 and phase 2
 trials conducted in India and Africa but no efficacy trials have been undertaken.
 Prequalification was granted on the assumption that the high level of immunogenicity
 demonstrated in African populations would be reflected by a similar degree of efficacy. This
 is likely, but it is important that the efficacy of this vaccine is established definitively
 before large sums are spent on deploying the vaccine across the African meningitis belt.
 Therefore, a case control study to determine the efficacy of MenAfriVac in preventing
 serogroup A meningococcal meningitis in Mali and Niger is proposed.

 A case-control study will be conducted in Mali and in Niger during the 2011, 2012 and 2013
 meningitis seasons. Cases of meningitis will be detected through existing routine
 surveillance systems and their etiology established using standard microbiology or rapid
 diagnostic tests. Cases of proven serogroup A meningococcal meningitis (culture, antigen or
 PCR positive) will be matched with two hospital and two community controls who will, in turn,
 be matched with the cases for age and place of residence. A questionnaire will be
 administered to cases and controls which asks about previous meningococcal vaccination and
 other risk factors for meningococcal disease which might confound or modify assessment of the
 impact of vaccination with MenAfriVac. A blood sample will be collected for measurement of
 serogroup A meningococcal bactericidal and tetanus antibodies, as well as total
 immunoglobulin levels. Determination of vaccination status will be facilitated by the fact
 that vaccination cards will be issued to all recipients at the time of vaccination by the
 mass vaccination teams. Vaccine efficacy will be determined by comparing the odds of exposure
 to MenAfriVac in cases and controls.
Inclusion Criteria:

 - Cases: i)consent to participate; ii) Laboratory confirmed serogroup A meningococcal
 disease established by examination of the CSF (turbid CSF or a white cell > 10 per ul) and
 evidence of a serogroup A meningococcal infection established by (a) culture of serogroup A
 meningococci from the cerebrospinal fluid, blood or other normally sterile fluid, (b) a
 positive CSF latex test for serogroup A meningococcal antigen, (c) a positive serogroup A
 dipstick assay or (d) a positive CSF PCR for serogroup A meningococcal infection; iii) 1 to
 29 years old.

 iii) In target 1-29 year age group at the time of vaccination with MenAfriVac.

 - Hospital controls: i)consent to participate; ii)patients admitted to the hospital with an
 acute illness other than meningitis, matched to cases for age and sex

 -Community controls: i)consent to participate; ii)Healthy members of the community, matched
 to cases for age and sex

 Exclusion Criteria:

 -  Case:

 i)Refusal to participate in the study; ii) infants<1 year old and adults>29 years old

 -  Hospital controls:

 i)Refusal to participate in the study; ii)Previous history of meningitis; iii)
 Presence of symptoms that could indicate meningitis

 -  Community controls:

 i)Refusal to participate in the study; ii)Previous history of meningitis; iii)
 Presence of symptoms that could indicate meningitis