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CSU 65/2009: NON-SPECIFIC MORTALITY IMPACT ASSOCIATED WITH VACCINATION

Friday, 23rd of October 2009

                                  CSU 65/2009: NON-SPECIFIC MORTALITY  IMPACT ASSOCIATED WITH VACCINATION
 
 Those interested in non-specific mortality effects associated with infant
 vaccinations may wish to read  this study from Malawi.
 
 From the authors' discussion:
 
 ‘Given the claim that DPT given simultaneously with or after measles
 vaccination might be detrimental to child survival (Breiman et al. 2004),
 it is of interest that 9% of infants in this population had received this
 schedule. This was associated with indicators of poor socio-economic
 status, which are likely to confound the effects of vaccination schedules
 on child survival. The evidence presented challenges the hypothesis of
 'non-specific' effects of vaccines on mortality (Aaby et al. 2004a,b,
 2005a,b; Aaby & Jensen 2005). ’
 
 Summary of the study is reproduced below; full text is at
 http://www3.interscience.wiley.com/cgi-bin/fulltext/119417363/HTMLSTART
 
 Good reading.
 
 Bob Davis
 
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 1: Trop Med Int Health. 2008 Jan;13(1):129-38.
 Ascertainment of childhood vaccination histories in northern Malawi.
 
 Jahn A, Floyd S, Mwinuka V, Mwafilaso J, Mwagomba D, Mkisi RE, Katsulukuta
 A, Khunga A, Crampin AC, Branson K, McGrath N, Fine PE.
 Karonga Prevention Study, Chilumba, Malawi. andreas.jahn@lshtm.ac.uk
 
 OBJECTIVE: To assess factors related to recorded vaccine uptake, which may
 confound the evaluation of vaccine impact.
 
 METHODS: Analysis of documented vaccination histories of children under 5
 years and demographic and socio-economic characteristics collected by a
 demographic surveillance system in Karonga District, Malawi. Associations
 between deviations from the standard vaccination schedule and
 characteristics that are likely to be associated with increased mortality
 were determined by multivariate logistic regression.
 
 RESULTS: Approximately 78% of children aged 6-23 months had a vaccination
 document, declining to <50% by 5 years of age. Living closer to an under-5
 clinic, having a better educated father, and both parents being alive were
 associated with having a vaccination document. For a small percentage of
 children, vaccination records were incomplete and/or faulty. Vaccination
 uptake was high overall, but delayed among children living further from the
 nearest under-5 clinic or from poorer socio-economic backgrounds.
 Approximately 9% of children had received their last dose of DPT with or
 after measles vaccine. These children were from relatively less educated
 parents, and were more likely to have been born outside the health
 services.
 
 CONCLUSIONS: Though overall coverage in this community was high and
 variation in coverage according to child or parental characteristics small,
 there was strong evidence of more timely coverage among children from
 better socio-economic conditions and among those who lived closer to health
 facilities. These factors are likely to be strong confounders in the
 association of vaccinations with mortality, and may offer an alternative
 explanation for the non-specific mortality impact of vaccines described by
 other studies.
 PMID: 18291011 [PubMed - indexed for MEDLINE]