Evaluation of serogroup A meningococcal vaccines in Africa: a demonstration project

Meningitis and Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Journal of Health Population and Nutrition (Impact Factor: 1.04). 10/2004; 22(3):275-85.
Source: PubMed

ABSTRACT Endemic and epidemic meningococcal disease constitutes a major public-health problem in African countries of the 'meningitis belt' where incidence rates of the disease are many-fold higher (up to 25 cases per 100,000 population) than those in industrialized countries, and epidemics of meningococcal disease occur with rates as high as 1,000 cases per 100,000 people. Using the precedent established during the licensing of conjugate vaccines against Haemophilus influenzae type b and serogroup C meningococci and components of currently-licensed meningococcal polysaccharide vaccines, new meningococcal conjugate vaccines will likely be licensed using immunological endpoints as surrogates for clinical protection. Post-licensure evaluation of vaccine effectiveness will, therefore, be of increased importance. One vaccine being developed is the serogroup A meningococcal (Men A) conjugate vaccine produced by the Meningitis Vaccine Project (MVP), a partnership between the World Health Organization and the Program for Applied Technology in Health. This vaccine will likely be the first meningococcal conjugate vaccine introduced on a large scale in Africa. This paper summarizes the general steps required for vaccine development, reviews the use of immunogenicity criteria as a licensing strategy for new meningococcal vaccines, and discusses plans for evaluating the impact of a meningococcal A conjugate vaccine in Africa. Impact of this vaccine will be measured during a vaccine-demonstration project that will primarily measure the effectiveness of vaccine. Other studies will include evaluations of safety, vaccine coverage, impact on carriage and herd immunity, and prevention-effectiveness studies.

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Available from: Montse Soriano-Gabarro, Sep 28, 2015
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    • "Antimicrobial agents are very effective against these diseases [3] and vaccines were available for much of the second half of the twentieth century, but it was the development of conjugate protein–polysaccharide vaccines which has brought the prospect of effective disease control and the potential for an ‘endgame’ [4]. The first such vaccines to be used were the H. influenzae serotype b (Hib) vaccines [5,6], followed by vaccines against serogroup C meningococci (MenC) [7], multivalent vaccines against pneumococci [8–10] and vaccines against other meningococcal serogroups including the MenAfriVac serogroup A vaccine [11]. These vaccines have led to marked reductions in invasive disease, have excellent safety and efficacy profiles, and are extremely effective in settings where high rates of immunization are attained [4,12]. "
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    ABSTRACT: The development and implementation of conjugate polysaccharide vaccines against invasive bacterial diseases, specifically those caused by the encapsulated bacteria Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae, has been one of the most effective public health innovations of the last 25 years. These vaccines have resulted in significant reductions in childhood morbidity and mortality worldwide, with their effectiveness due in large part to their ability to induce long-lasting immunity in a range of age groups. At the population level this immunity reduces carriage and interrupts transmission resulting in herd immunity; however, these beneficial effects can be counterbalanced by the selection pressures that immunity against carriage can impose, potentially promoting the emergence and spread of virulent vaccine escape variants. Studies following the implementation of meningococcal serogroup C vaccines improved our understanding of these effects in relation to the biology of accidental pathogens such as the meningococcus. This understanding has enabled the refinement of the implementation of conjugate polysaccharide vaccines against meningitis-associated bacteria, and will be crucial in maintaining and improving vaccine control of these infections. To date there is little evidence for the spread of virulent vaccine escape variants of the meningococcus and H. influenzae, although this has been reported in pneumococci.
    Philosophical Transactions of The Royal Society B Biological Sciences 08/2013; 368(1623):20120147. DOI:10.1098/rstb.2012.0147 · 7.06 Impact Factor
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    • "The forthcoming group A conjugate vaccine for the control of meningococcal disease in Africa is likely to radically change the epidemiology of meningitis epidemics across the continent [1] and will require a reassessment of the research needs underpinning control activities to facilitate the optimal utilization of resources. "
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    ABSTRACT: Epidemics of meningococcal meningitis in Africa have plagued the continent for over a century. These epidemics have a strong association with the environment and efforts are being made to develop models to predict both their location and their incidence. This review describes the predictive models based on climate/environmental information currently available, describes work in progress, and presents evidence that the distribution of the epidemics is changing in a pattern that is compatible with changes in the environment. Discussion of priorities for research in the context of the new conjugate vaccines in Africa is also provided.
    Vaccine 10/2007; 25 Suppl 1(1):A12-7. DOI:10.1016/j.vaccine.2007.04.034 · 3.62 Impact Factor
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    ABSTRACT: Neisseria meningitidis bacteria of serogroup A are causing recurring meningitis epidemics on the African continent. An outer membrane vesicle (OMV) vaccine against serogroup A meningococci made from a subgroup III serogroup A meningococcal strain was previously shown to induce antibodies with serum bactericidal activity (SBA) in mice. We have here further investigated the properties of OMV vaccines made from five different subgroup III serogroup A meningococcal strains grown in a synthetic medium with low iron content. In addition to the major outer membrane proteins (PorA, PorB, RmpM, Opa and OpcA), small amounts of the NadA, TdfH, Omp85, FetA, FbpA and NspA outer membrane proteins, as well as lipooligosaccharides, were detected in the vaccines. The OMV vaccines were used to immunise mice. Anti-meningococcal IgG antibodies in the mouse sera were analysed by immunoblotting and by enzyme-linked immunosorbent assay against OMVs, and against live meningococcal cells in SBA and a flow-cytometric assay. The vaccines induced antibodies with high SBA and opsonophagocytic activity. The strongest IgG responses were directed against PorA. Significant SBA responses were also observed against a subgroup III strain, which did not express PorA, whereas no SBA was observed against a clone IV-1 serogroup A strain. An OMV vaccine from serogroup A meningococci may be an alternative to polysaccharide and conjugate polysaccharide vaccines for Africa.
    Vaccine 06/2005; 23(29):3762-74. DOI:10.1016/j.vaccine.2005.02.021 · 3.62 Impact Factor
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