Continuing Effectiveness of Serogroup A Meningococcal Conjugate Vaccine, Chad, 2013 - Volume 21, Number 1—January 2015 - Emerging Infectious Disease journal - CDC

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Continuing Effectiveness of Serogroup A Meningococcal Conjugate Vaccine, Chad, 2013 - Volume 21, Number 1—January 2015 - Emerging Infectious Disease journal - CDC

Volume 21, Number 1—January 2015

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Continuing Effectiveness of Serogroup A Meningococcal Conjugate Vaccine, Chad, 2013

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• The Study
• Conclusions
• Suggested Citation

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• Figure 1
• Figure 2

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Kadidja Gamougam, Doumagoum M. Daugla, Jacques Toralta, Cyriaque Ngadoua, Florence Fermon, Anne-Laure Page, Mamoudou H. Djingarey, Dominique A. Caugant, Olivier Manigart, Caroline L. Trotter, James M. Stuart , Brian M. Greenwood, and Brian M. Greenwood.

Author affiliations: Hôpital Général de Référence Nationale, N’Djamena, Chad (K. Gamougam); Centre de Support en Santé International, N’Djamena (D.M. Daugla, J. Toralta); Ministere de la Santé Publique, N’Djamena (C. Ngadoua); Epicentre– Médecins sans Frontières, Paris, France (F. Fermon, A.-L. Page); World Health Organization Intercountry Support Team, Ouagadougou, Burkina Faso (M.H. Djingarey); Norwegian Institute for Public Health, Oslo, Norway (D.A.Caugant); London School of Hygiene & Tropical Medicine, London, UK (O. Manigart, J.M. Stuart, B.M. Greenwood); University of Cambridge, Cambridge, UK (C.L.Trotter)

Suggested citation for this article

Abstract

In 2011, vaccination with a serogroup A meningococcal polysaccharide conjugate vaccine was implemented in 3 of 23 regions in Chad. Cases of meningitis declined dramatically in vaccinated areas, but an epidemic continued in the rest of Chad. In 2012, the remaining Chad population was vaccinated, and the epidemic was halted.

For >100 years, countries in the meningitis belt of Africa have experienced intermittent epidemics of meningococcal meningitis, caused mainly by the serogroup A meningococcus (1). After development and prequalification of a new serogroup A meningococcal polysaccharide/tetanus toxoid conjugate vaccine (PsA-TT) in 2009 (2), vaccination with PsA-TT across the meningitis belt commenced in 2010, starting with persons 1–29 years of age in Burkina Faso and parts of Mali and Niger (3). Little transmission of the serogroup A meningococcus was occurring in these countries at the time of vaccine introduction, making evaluation of its effectiveness difficult.

Figure 1. Areas of Chad in which vaccination with serogroup A meningococcal polysaccharide/tetanus toxoid conjugate vaccine was implemented in 2011 (white) and 2012 (gray).

In contrast, in Chad, PsA-TT was introduced in the middle of a serogroup A meningococcal epidemic, and vaccination with PsA-TT commenced at the end of 2011, shortly before the 2012 epidemic season. At this time, vaccination of persons 1–29 years of age (target 1.8 million) was undertaken in the capital N’Djamena, Mayo Kebbi Est, and Chari Baguirmi (4), designated here as the N’Djamena regions (Figure 1). In 2012, the vaccination program was extended to the rest of the country (target 5.9 million) (Figure 1). During the 2012 meningitis season, the incidence of meningitis decreased by >90% in vaccinated areas compared with the rest of the country, and a similar reduction in the incidence of carriage of serogroup A Neisseria meningitidis was found, as reported previously (4). We report on the incidence of meningitis during the 2013 meningitis season after vaccination of persons 1–29 years of age in areas with no prior vaccination program.

Dr. Gamougam is head microbiologist at the reference laboratory of the Hôpital Générale de Référence Nationale, N’Djaména, Chad. Her research interest is bacterial meningitis.

Acknowledgments

We acknowledge the major contributions of the Meningitis Vaccine Project and their colleagues in the control of epidemic meningitis in Africa through the development of PsA-TT.

This study was supported by the MenAfriCar consortium with funding from the Bill and Melinda Gates Foundation and the Wellcome Trust.

References

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Figures

• Figure 1. Areas of Chad in which vaccination with serogroup A meningococcal polysaccharide/tetanus toxoid conjugate vaccine was implemented in 2011 (white) and 2012 (gray).
• Figure 2. Incidence (no. cases/100,000 population) during weeks 1–26 of reported cases of meningitis in regions of Chad where persons 1–29 years of age were vaccinated with serogroup A meningococcal polysaccharide/tetanus...

Table

• Table. Diagnoses of suspected meningitis cases from CSF specimens, Chad, weeks 1–26, 2010–2013

Suggested citation for this article: Gamougam K, Daugla DM, Toralta J, Ngadoua C, Fermon F, Page AL, et al. Continuing effectiveness of serogroup A meningococcal conjugate vaccine, Chad, 2013. Emerg Infect Dis [Internet]. 2015 Jan [date cited]. http://dx.doi.org/10.3201/eid2101.140256

DOI: 10.3201/eid2101.140256