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