title: Sex-differential and non-specific effects of routine vaccinations in a rural area with low vaccination coverage: an observational study from Senegal.
abstract: BACKGROUND
  We examined the potential sex-differential and non-specific effects of bacille Calmette-Guérin (BCG), diphtheria-tetanus-pertussis (DTP) and measles vaccine (MV) in a rural area of Senegal.
  
  
  METHODS
  The 4133 children born in the area between 1996 and 1999 were included in the study. Vaccinations were provided at three health centres. Vaccine information was collected through 3-monthly home visits. The survival analysis compared the effects of BCG and DTP according to the following sequence of vaccinations: BCG-first, BCG+DTP1-first, or DTP1-first. We compared DTP and MV between 9 and 24 months of age, as 9 months is the minimum age for MV.
  
  
  RESULTS
  At 12 months the vaccination coverage was 44%, 46% and 9%, respectively, for BCG, DTP1 and MV. Most children received BCG+DTP1-first and this combination was associated with a significantly lower mortality rate ratio (MRR) of 0.69 (0.53-0.89) compared with unvaccinated children. There was no benefit for children receiving BCG-first or DTP1-first. The female-male MRR was 0.79 (0.64-0.96) among unvaccinated children, but was significantly inversed with 1.45 (1.00-2.10) for children receiving DTP vaccination (test of homogeneity, p=0.006). Children who had received DTP simultaneously with MV or DTP after MV had significantly higher mortality (MRR=2.59 [1.32-5.07]) compared with children having MV-only as their most recent vaccination. After 9 months, the female-male MRR was 0.61 (0.31-1.19) for measles-vaccinated children but remained 1.54 (1.03-2.31) for DTP-vaccinated children who had not received MV (p=0.01).
  
  
  CONCLUSIONS
  The sequence of routine vaccinations is important for the overall impact on child survival and these vaccines are associated with sex-differential effects.
authors.affiliation: Institut de Recherche pour le Développement (IRD), Laboratoire de Paludologie, Epidémiologie et Zoologie afrotropicales, BP 1386, Dakar, Senegal Bandim Health Project, Indepth Network, Apartado 861, Bissau, Guinea-Bissau p.aaby@bandim.org.
authors.forename: Peter
authors.initials: P
authors.lastname: Aaby
authors.affiliation: Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Jens
authors.initials: J
authors.lastname: Nielsen
authors.affiliation: Research Center for Vitamins and Vaccines (CVIVA), Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Christine S
authors.initials: CS
authors.lastname: Benn
authors.affiliation: Institut de Recherche pour le Développement (IRD), Laboratoire de Paludologie, Epidémiologie et Zoologie afrotropicales, BP 1386, Dakar, Senegal.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Trape
mesh_terms: D001500:BCG Vaccine / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008458:Measles Vaccine / Q000008:administration & dosage*; D012424:Rural Population / Q000706:statistics & numerical data*; D012675:Senegal / Q000453:epidemiology; D012737:Sex Factors; D014611:Vaccination
chemical_list: D001500:BCG Vaccine; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D008458:Measles Vaccine
keywords: BCG; DTP; Measles vaccine; Non-specific effects of vaccines; Sequence of vaccinations; Sex-differential effects