Hornshøj L, Benn CS, Fernandes M, Rodrigues A, Aaby P and AB Fisker. 2012. Vaccination Coverage and Out-of-Sequence Vaccinations in Rural Guinea-Bissau: An Observational Cohort Study. BMJ Open, 2(6).
The WHO aims for 90% coverage of the Expanded Program on Immunization (EPI), which in Guinea-Bissau included bacillus Calmette-Guérin vaccine (BCG) at birth, 3 doses of diphtheria-tetanus-pertussis vaccine (DTP) and oral polio vaccine (OPV) at 6, 10 and 14 weeks and measles vaccine (MV) at 9 months when this study was conducted. The WHO assesses coverage by 12 months of age. The sequence of vaccines may have an effect on child mortality, but is not considered in official statistics or assessments of programme performance.

In this observational cohort study from rural Guinea-Bissau we assessed vaccination coverage and frequency of out-of-sequence vaccinations by 12 and 24 months of age using the Bandim Health Project’s rural Health and Demographic Surveillance System. It covers 258 randomly selected villages in all regions of Guinea-Bissau. Between 2003 and 2009 vaccination status by 12 months of age was assessed for 5806 children aged 12-23 months; vaccination status by 24 months of age was assessed for 3792 children aged 24-35 months.

We found that only half of 12-month-old children had completed all EPI vaccinations, but coverage increased to 65% among 24-month-old children. Many children received vaccines out-of-sequence: by 12 months of age 54% of BCG vaccinated children had received DTP with or before BCG and 28% of measles vaccinated children had received DTP with or after MV. By 24 months of age the proportion of out-of-sequence vaccinations was 58% and 35%, respectively, for BCG and MV. The low vaccination coverage and the high frequency of out-of-sequence vaccinations highlight the need to improve vaccination services.
This study was supported by the Danish Medical Research Council, the Aase and Ejnar Danielsen's Foundation and DANIDA. The Bandim Health Project received support from DANIDA to conduct their rural HDSS. CVIVA receives support from the Danish National Research Foundation. CSB is funded by the European Research Council (ERC-2009-StG, grant agreement no. 243149). PA holds a research professorship grant from the Novo Nordic Foundation. Funding agencies had no hand in study design, execution, data analysis, data interpretation or the writing of this paper.

Last revised 10 February 2013