title: Effect of the introduction of pneumococcal conjugate vaccination on invasive pneumococcal disease in The Gambia: a population-based surveillance study.
abstract: Little information is available about the effect of pneumococcal conjugate vaccines (PCVs) in low-income countries. We measured the effect of these vaccines on invasive pneumococcal disease in The Gambia where the 7-valent vaccine (PCV7) was introduced in August, 2009, followed by the 13-valent vaccine (PCV13) in May, 2011.
  
  
  
  We conducted population-based surveillance for invasive pneumococcal disease in individuals aged 2 months and older who were residents of the Basse Health and Demographic Surveillance System (BHDSS) in the Upper River Region, The Gambia, using standardised criteria to identify and investigate patients. Surveillance was done between May, 2008, and December, 2014. We compared the incidence of invasive pneumococcal disease between baseline (May 12, 2008-May 11, 2010) and after the introduction of PCV13 (Jan 1, 2013-Dec 31, 2014), adjusting for changes in case ascertainment over time.
  
  
  
  We investigated 14 650 patients, in whom we identified 320 cases of invasive pneumococcal disease. Compared with baseline, after the introduction of the PCV programme, the incidence of invasive pneumococcal disease decreased by 55% (95% CI 30-71) in the 2-23 months age group, from 253 to 113 per 100 000 population. This decrease was due to an 82% (95% CI 64-91) reduction in serotypes covered by the PCV13 vaccine. In the 2-4 years age group, the incidence of invasive pneumococcal disease decreased by 56% (95% CI 25-75), from 113 to 49 cases per 100 000, with a 68% (95% CI 39-83) reduction in PCV13 serotypes. The incidence of non-PCV13 serotypes in children aged 2-59 months increased by 47% (-21 to 275) from 28 to 41 per 100 000, with a broad range of serotypes. The incidence of non-pneumococcal bacteraemia varied little over time.
  
  
  
  The Gambian PCV programme reduced the incidence of invasive pneumococcal disease in children aged 2-59 months by around 55%. Further surveillance is needed to ascertain the maximum effect of the vaccine in the 2-4 years and older age groups, and to monitor serotype replacement. Low-income and middle-income countries that introduce PCV13 can expect substantial reductions in invasive pneumococcal disease.
  
  
  
  GAVI's Pneumococcal vaccines Accelerated Development and Introduction Plan (PneumoADIP), Bill & Melinda Gates Foundation, and the UK Medical Research Council.
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia; Murdoch Childrens Research Institute, Parkville, Melbourne, Australia; London School of Hygiene & Tropical Medicine, London, UK. Electronic address: gmackenzie@mrc.gm.
authors.forename: Grant A
authors.initials: GA
authors.lastname: Mackenzie
authors.affiliation: Centre for International Health, University of Otago, Dunedin, New Zealand.
authors.forename: Philip C
authors.initials: PC
authors.lastname: Hill
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Jeffries
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Ilias
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authors.lastname: Hossain
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Uchendu
authors.initials: U
authors.lastname: Uchendu
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: David
authors.initials: D
authors.lastname: Ameh
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Malick
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authors.lastname: Ndiaye
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Oyedeji
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authors.lastname: Adeyemi
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Jayani
authors.initials: J
authors.lastname: Pathirana
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Yekini
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authors.lastname: Olatunji
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Bade
authors.initials: B
authors.lastname: Abatan
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Bilquees S
authors.initials: BS
authors.lastname: Muhammad
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Augustin E
authors.initials: AE
authors.lastname: Fombah
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Debasish
authors.initials: D
authors.lastname: Saha
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Ian
authors.initials: I
authors.lastname: Plumb
authors.affiliation: The National Hospital, Central Area, Garki, Abuja, Nigeria.
authors.forename: Aliu
authors.initials: A
authors.lastname: Akano
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Bernard
authors.initials: B
authors.lastname: Ebruke
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Readon C
authors.initials: RC
authors.lastname: Ideh
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Bankole
authors.initials: B
authors.lastname: Kuti
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Peter
authors.initials: P
authors.lastname: Githua
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Olutunde
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Ogochukwu
authors.initials: O
authors.lastname: Ofordile
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Edward
authors.initials: E
authors.lastname: Green
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Effua
authors.initials: E
authors.lastname: Usuf
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Henry
authors.initials: H
authors.lastname: Badji
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Usman N A
authors.initials: UNA
authors.lastname: Ikumapayi
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Manjang
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Rasheed
authors.initials: R
authors.lastname: Salaudeen
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: E David
authors.initials: ED
authors.lastname: Nsekpong
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Sheikh
authors.initials: S
authors.lastname: Jarju
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia; London School of Hygiene & Tropical Medicine, London, UK; Warwick Medical School, University of Warwick, Coventry, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Antonio
authors.affiliation: Ministry of Health and Social Welfare, Gambia Government, Kotu, The Gambia.
authors.forename: Sana
authors.initials: S
authors.lastname: Sambou
authors.affiliation: Ministry of Health and Social Welfare, Gambia Government, Kotu, The Gambia.
authors.forename: Lamin
authors.initials: L
authors.lastname: Ceesay
authors.affiliation: Ministry of Health and Social Welfare, Gambia Government, Kotu, The Gambia.
authors.forename: Yamundow
authors.initials: Y
authors.lastname: Lowe-Jallow
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Momodou
authors.initials: M
authors.lastname: Jasseh
authors.affiliation: Murdoch Childrens Research Institute, Parkville, Melbourne, Australia; London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: Kim
authors.initials: K
authors.lastname: Mulholland
authors.affiliation: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Knoll
authors.affiliation: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Orin S
authors.initials: OS
authors.lastname: Levine
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia; Centre for International Health, University of Otago, Dunedin, New Zealand; Department of Paediatrics: Child and Youth Health, University of Auckland, Auckland, New Zealand.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Howie
authors.affiliation: GlaxoSmithKline Vaccines, Wavre, Belgium.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Adegbola
authors.affiliation: London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Greenwood
authors.affiliation: Medical Research Council, The Gambia Unit, Atlantic Road, Fajara, The Gambia.
authors.forename: Tumani
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authors.lastname: Corrah
mesh_terms: D002675:Child, Preschool; D005260:Female; D005714:Gambia; D000069443:Heptavalent Pneumococcal Conjugate Vaccine / Q000008:administration & dosage*; D006801:Humans; D007155:Immunologic Factors; D007223:Infant; D008297:Male; D011008:Pneumococcal Infections / Q000276:immunology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011159:Population Surveillance; D013296:Streptococcus pneumoniae / Q000276:immunology; D014611:Vaccination / Q000379:methods*; D018074:Vaccines, Conjugate / Q000276:immunology*
chemical_list: C538862:13-valent pneumococcal vaccine; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D007155:Immunologic Factors; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate