title: Effect of a serogroup A meningococcal conjugate vaccine (PsA-TT) on serogroup A meningococcal meningitis and carriage in Chad: a community study [corrected].
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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  The Bill & Melinda Gates Foundation, the Wellcome Trust, and Médecins Sans Frontères.
authors.affiliation: Centre de Support en Santé International (CSSI), N'Djamena, Chad.
authors.forename: D M
authors.initials: DM
authors.lastname: Daugla
authors.affiliation: Centre de Support en Santé International (CSSI), N'Djamena, Chad.
authors.forename: J P
authors.initials: JP
authors.lastname: Gami
authors.affiliation: Centre de Support en Santé International (CSSI), N'Djamena, Chad.
authors.forename: K
authors.initials: K
authors.lastname: Gamougam
authors.affiliation: Centre de Support en Santé International (CSSI), N'Djamena, Chad.
authors.forename: N
authors.initials: N
authors.lastname: Naibei
authors.affiliation: Centre de Support en Santé International (CSSI), N'Djamena, Chad.
authors.forename: L
authors.initials: L
authors.lastname: Mbainadji
authors.affiliation: Centre de Support en Santé International (CSSI), N'Djamena, Chad.
authors.forename: M
authors.initials: M
authors.lastname: Narbé
authors.affiliation: Centre de Support en Santé International (CSSI), N'Djamena, Chad.
authors.forename: J
authors.initials: J
authors.lastname: Toralta
authors.affiliation: Centre de Support en Santé International (CSSI), N'Djamena, Chad.
authors.forename: B
authors.initials: B
authors.lastname: Kodbesse
authors.affiliation: Ministry of Public Health, N'Djamena, Chad.
authors.forename: C
authors.initials: C
authors.lastname: Ngadoua
authors.affiliation: Epicentre, Médecins sans Frontères, Paris, France.
authors.forename: M E
authors.initials: ME
authors.lastname: Coldiron
authors.affiliation: Epicentre, Médecins sans Frontères, Paris, France.
authors.forename: F
authors.initials: F
authors.lastname: Fermon
authors.affiliation: Epicentre, Médecins sans Frontères, Paris, France.
authors.forename: A-L
authors.initials: AL
authors.lastname: Page
authors.affiliation: WHO Intercountry Support Team, Ougadougou, Burkina Faso.
authors.forename: M H
authors.initials: MH
authors.lastname: Djingarey
authors.affiliation: Department of Pandemic and Epidemic Diseases, WHO, Geneva, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Hugonnet
authors.affiliation: Department of Zoology, University of Oxford, Oxford, UK.
authors.forename: O B
authors.initials: OB
authors.lastname: Harrison
authors.affiliation: Department of Zoology, University of Oxford, Oxford, UK.
authors.forename: L S
authors.initials: LS
authors.lastname: Rebbetts
authors.affiliation: Department of Zoology, University of Oxford, Oxford, UK.
authors.forename: Y
authors.initials: Y
authors.lastname: Tekletsion
authors.affiliation: Department of Zoology, University of Oxford, Oxford, UK.
authors.forename: E R
authors.initials: ER
authors.lastname: Watkins
authors.affiliation: Department of Zoology, University of Oxford, Oxford, UK.
authors.forename: D
authors.initials: D
authors.lastname: Hill
authors.affiliation: Norwegian Institute for Public Health, Oslo, Norway.
authors.forename: D A
authors.initials: DA
authors.lastname: Caugant
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: D
authors.initials: D
authors.lastname: Chandramohan
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Hassan-King
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: O
authors.initials: O
authors.lastname: Manigart
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Nascimento
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Woukeu
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
authors.forename: C
authors.initials: C
authors.lastname: Trotter
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Stuart
authors.affiliation: Department of Zoology, University of Oxford, Oxford, UK.
authors.forename: McJ
authors.initials: M
authors.lastname: Maiden
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. Electronic address: brian.greenwood@lshtm.ac.uk.
authors.forename: B M
authors.initials: BM
authors.lastname: Greenwood
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002353:Carrier State / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control; D002596:Chad / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D058872:Epidemics; D006801:Humans; D015994:Incidence; D007223:Infant; D008585:Meningitis, Meningococcal / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control*; D022401:Meningococcal Vaccines; D038381:Neisseria meningitidis, Serogroup A / Q000302:isolation & purification*; D011159:Population Surveillance / Q000379:methods; D014611:Vaccination; D055815:Young Adult
chemical_list: C573970:MenAfriVac; D022401:Meningococcal Vaccines
references.citation: Minerva Med. 2006 Apr;97(2):161-73
references.pmid: 16760855
references.citation: PLoS One. 2012;7(9):e46019
references.pmid: 23029368
references.citation: Clin Infect Dis. 2013 Feb;56(3):354-63
references.pmid: 23087396
references.citation: MMWR Morb Mortal Wkly Rep. 2012 Dec 21;61(50):1022-4
references.pmid: 23254256
references.citation: Vaccine. 2009 Jun 24;27 Suppl 2:B64-70
references.pmid: 19464092
references.citation: Hum Vaccin. 2010 Apr;6(4):360-5
references.pmid: 20372072
references.citation: Acta Trop. 1995 Jun;59(3):211-22
references.pmid: 7572427
references.citation: Microbiology (Reading). 2002 Jun;148(Pt 6):1813-1819
references.pmid: 12055301
references.citation: Wkly Epidemiol Rec. 2010 Feb 19;85(8):47-63
references.pmid: 20210043
references.citation: J Clin Microbiol. 2005 Oct;43(10):5129-35
references.pmid: 16207974
references.citation: N Engl J Med. 2011 Jun 16;364(24):2293-304
references.pmid: 21675889
references.citation: Microbiology (Reading). 2012 Jun;158(Pt 6):1570-1580
references.pmid: 22422752
references.citation: Emerg Infect Dis. 2011 Nov;17(11):2070-2
references.pmid: 22099102
references.citation: Lancet Infect Dis. 2012 Oct;12(10):757-64
references.pmid: 22818241
references.citation: J Clin Microbiol. 2012 Mar;50(3):702-8
references.pmid: 22170919
references.citation: Bull World Health Organ. 1996;74(2):181-7
references.pmid: 8706234
references.citation: Mol Microbiol. 1994 Apr;12(2):253-65
references.pmid: 8057850
references.citation: Bull World Health Organ. 1993;71(3-4):311-5
references.pmid: 8324849
references.citation: Vaccine. 2012 May 30;30 Suppl 2:B40-5
references.pmid: 22607898
references.citation: J Clin Microbiol. 2001 Mar;39(3):936-42
references.pmid: 11230407
references.citation: Med Trop (Mars). 1969 Jul-Aug;29(4):443-54
references.pmid: 5403094
references.citation: Vaccine. 2013 Mar 15;31(12):1597-603
references.pmid: 23337027
references.citation: Vaccine. 2013 Mar 1;31(11):1453-7
references.pmid: 23273967
references.citation: Trop Med Int Health. 2012 Dec;17(12):1478-91
references.pmid: 22947250
references.citation: Bull Soc Pathol Exot. 2004 Aug;97(3):183-8
references.pmid: 15462200
references.citation: Lancet. 2002 May 25;359(9320):1829-31
references.pmid: 12044380
references.citation: PLoS One. 2012;7(1):e29116
references.pmid: 22276104