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. 2014 Jan 4;383(9911):40-47.
doi: 10.1016/S0140-6736(13)61612-8. Epub 2013 Sep 12.

Effect of a serogroup A meningococcal conjugate vaccine (PsA-TT) on serogroup A meningococcal meningitis and carriage in Chad: a community study [corrected]

D M Daugla  1 , J P Gami  1 , K Gamougam  1 , N Naibei  1 , L Mbainadji  1 , M Narbé  1 , J Toralta  1 , B Kodbesse  1 , C Ngadoua  2 , M E Coldiron  3 , F Fermon  3 , A-L Page  3 , M H Djingarey  4 , S Hugonnet  5 , O B Harrison  6 , L S Rebbetts  6 , Y Tekletsion  6 , E R Watkins  6 , D Hill  6 , D A Caugant  7 , D Chandramohan  8 , M Hassan-King  8 , O Manigart  8 , M Nascimento  8 , A Woukeu  8 , C Trotter  9 , J M Stuart  8 , McJ Maiden  6 , B M Greenwood  10
Affiliations

Effect of a serogroup A meningococcal conjugate vaccine (PsA-TT) on serogroup A meningococcal meningitis and carriage in Chad: a community study [corrected]

D M Daugla et al. Lancet. .

Erratum in

  • Lancet. 2014 Jan 4;383(9911):30

Abstract

Background: A serogroup A meningococcal polysaccharide-tetanus toxoid conjugate vaccine (PsA-TT, MenAfriVac) was licensed in India in 2009, and pre-qualified by WHO in 2010, on the basis of its safety and immunogenicity. This vaccine is now being deployed across the African meningitis belt. We studied the effect of PsA-TT on meningococcal meningitis and carriage in Chad during a serogroup A meningococcal meningitis epidemic.

Methods: We obtained data for the incidence of meningitis before and after vaccination from national records between January, 2009, and June, 2012. In 2012, surveillance was enhanced in regions where vaccination with PsA-TT had been undertaken in 2011, and in one district where a reactive vaccination campaign in response to an outbreak of meningitis was undertaken. Meningococcal carriage was studied in an age-stratified sample of residents aged 1-29 years of a rural area roughly 13-15 and 2-4 months before and 4-6 months after vaccination. Meningococci obtained from cerebrospinal fluid or oropharyngeal swabs were characterised by conventional microbiological and molecular methods.

Findings: Roughly 1·8 million individuals aged 1-29 years received one dose of PsA-TT during a vaccination campaign in three regions of Chad in and around the capital N'Djamena during 10 days in December, 2011. The incidence of meningitis during the 2012 meningitis season in these three regions was 2·48 per 100,000 (57 cases in the 2·3 million population), whereas in regions without mass vaccination, incidence was 43·8 per 100,000 (3809 cases per 8·7 million population), a 94% difference in crude incidence (p<0·0001), and an incidence rate ratio of 0·096 (95% CI 0·046-0·198). Despite enhanced surveillance, no case of serogroup A meningococcal meningitis was reported in the three vaccinated regions. 32 serogroup A carriers were identified in 4278 age-stratified individuals (0·75%) living in a rural area near the capital 2-4 months before vaccination, whereas only one serogroup A meningococcus was isolated in 5001 people living in the same community 4-6 months after vaccination (adjusted odds ratio 0·019, 95% CI 0·002-0·138; p<0·0001).

Interpretation: PSA-TT was highly effective at prevention of serogroup A invasive meningococcal disease and carriage in Chad. How long this protection will persist needs to be established.

Funding: The Bill & Melinda Gates Foundation, the Wellcome Trust, and Médecins Sans Frontères.

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Figures

Figure 1
Figure 1
Reported cases of meningitis in Chad from 1930–2012 Arrows show the introduction of new control measures.
Figure 2
Figure 2
Areas of Chad vaccinated with PsA–TT in 2011, or in epidemic or alert situation during Jan–June 2012 Green shading shows the districts where mass vaccination of people aged 1–29 years was undertaken at the end of 2011, before the 2012 meningitis season. Red shading shows the districts where the alert or epidemic threshold was reached during the course of the 2012 meningitis season. PsA–TT=serogroup A meningococcal polysaccharide–tetanus toxoid conjugate vaccine.
Figure 3
Figure 3
Incidence of reported cases of meningitis in Chad, 2009–12 Vaccination with PsA–TT was undertaken in patients aged 1–29 years at the end of 2011 (arrow). PsA–TT=serogroup A meningococcal polysaccharide–tetanus toxoid conjugate vaccine.
See this image and copyright information in PMC

Comment in

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