title: The Introduction of Diphtheria-Tetanus-Pertussis and Oral Polio Vaccine Among Young Infants in an Urban African Community: A Natural Experiment.
abstract: BACKGROUND
  We examined the introduction of diphtheria-tetanus-pertussis (DTP) and oral polio vaccine (OPV) in an urban community in Guinea-Bissau in the early 1980s.
  
  
  METHODS
  The child population had been followed with 3-monthly nutritional weighing sessions since 1978. From June 1981 DTP and OPV were offered from 3months of age at these sessions. Due to the 3-monthly intervals between sessions, the children were allocated by birthday in a 'natural experiment' to receive vaccinations early or late between 3 and 5months of age. We included children who were <6months of age when vaccinations started and children born until the end of December 1983. We compared mortality between 3 and 5months of age of DTP-vaccinated and not-yet-DTP-vaccinated children in Cox proportional hazard models.
  
  
  RESULTS
  Among 3-5-month-old children, having received DTP (±OPV) was associated with a mortality hazard ratio (HR) of 5.00 (95% CI 1.53-16.3) compared with not-yet-DTP-vaccinated children. Differences in background factors did not explain the effect. The negative effect was particularly strong for children who had received DTP-only and no OPV (HR=10.0 (2.61-38.6)). All-cause infant mortality after 3months of age increased after the introduction of these vaccines (HR=2.12 (1.07-4.19)).
  
  
  CONCLUSIONS
  DTP was associated with increased mortality; OPV may modify the effect of DTP.
authors.affiliation: Bandim Health Project, Indepth Network, Apartado 861, Bissau, Guinea-Bissau.
authors.forename: Søren Wengel
authors.initials: SW
authors.lastname: Mogensen
authors.affiliation: Research Centre for Vitamins and Vaccines (CVIVA), Bandim Health Project, Statens Serum Institute, Artillerivej 5, 2300 Copenhagen S, Denmark.
authors.forename: Andreas
authors.initials: A
authors.lastname: Andersen
authors.affiliation: Bandim Health Project, Indepth Network, Apartado 861, Bissau, Guinea-Bissau.
authors.forename: Amabelia
authors.initials: A
authors.lastname: Rodrigues
authors.affiliation: Research Centre for Vitamins and Vaccines (CVIVA), Bandim Health Project, Statens Serum Institute, Artillerivej 5, 2300 Copenhagen S, Denmark; OPEN, Institute of Clinical Research, University of Southern Denmark/Odense University Hospital, 5000 Odense C, Denmark.
authors.forename: Christine S
authors.initials: CS
authors.lastname: Benn
authors.affiliation: Bandim Health Project, Indepth Network, Apartado 861, Bissau, Guinea-Bissau; Research Centre for Vitamins and Vaccines (CVIVA), Bandim Health Project, Statens Serum Institute, Artillerivej 5, 2300 Copenhagen S, Denmark. Electronic address: p.aaby@bandim.org.
authors.forename: Peter
authors.initials: P
authors.lastname: Aaby
mesh_terms: D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006169:Guinea-Bissau; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D008297:Male; D011055:Poliovirus Vaccine, Oral / Q000008:administration & dosage / Q000009:adverse effects*; D014505:Urban Population / Q000706:statistics & numerical data
chemical_list: D015721:Diphtheria-Tetanus-Pertussis Vaccine; D011055:Poliovirus Vaccine, Oral
keywords: DTP; Diphtheria-tetanus-pertussis vaccine; Measles vaccine; Non-specific effects of vaccines; Oral polio vaccine