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Assessment of childhood immunisation coverage

2009; Elsevier BV; Volume: 373; Issue: 9673 Linguagem: Inglês

10.1016/s0140-6736(09)60823-0

1474-547X

Peter Aaby, Christine Stabell Benn,

Influenza Virus Research Studies

Stephen Lim and colleagues1Lim SS Stein DB Charrow A Murray CJ Tracking progress towards universal childhood immunisation and the impact of global initiatives: a systematic analysis of three-dose diphtheria, tetanus, and pertussis immunisation coverage.Lancet. 2008; 372: 2031-2046Summary Full Text Full Text PDF PubMed Scopus (210) Google Scholar scrutinise coverage with the third dose of diphtheria-tetanus-pertussis vaccine (DTP3) in 193 countries. With donor emphasis on DTP3 coverage, it is not surprising that the national estimates might be inflated. Still, there is little doubt that DTP3 coverage has increased in recent decades.But maybe we should be more concerned about the health implications of this trend than about the accuracy of the estimate. From a public health perspective, the fact that DTP3 coverage is now higher than measles vaccine coverage in most African countries is of questionable value. Numerous studies have shown that measles vaccine is beneficial for child survival,2Aaby P Samb B Simondon F Coll Seck AM Knudsen K Whittle H Non-specific beneficial effect of measles immunisation: analysis of mortality studies from developing countries.BMJ. 1995; 311: 481-485Crossref PubMed Scopus (257) Google Scholar but there are conflicting data about the effect of DTP.DTP has frequently been associated with increased mortality in situations with herd immunity.3Aaby P Benn CS Nielsen J Lisse IM Rodrigues A Jensen H Estimating the effect of DTP vaccination on mortality in observational studies with incomplete vaccination data.Trop Med Int Health. 2007; 12: 15-24Crossref PubMed Google Scholar Furthermore, as a result of the drive to increase the DTP3 coverage, more children receive DTP simultaneously with or after measles vaccine. We have found consistently that DTP given simultaneously with measles vaccine (table) or after it4Aaby P Jensen H Samb B et al.Differences in female-male mortality after high-titre measles vaccine and association with subsequent vaccination with diphtheria-tetanus-pertussis and inactivated poliovirus: reanalysis of West African studies.Lancet. 2003; 361: 2183-2188Summary Full Text Full Text PDF PubMed Scopus (172) Google Scholar is associated with increased mortality compared with having measles vaccine alone as the most recent vaccine.TableMortality ratio for children receiving DTP together with measles vaccine compared with measles vaccine as most recent vaccineMortality ratio (95% CI)Malawi5·27 (1·1–25·0)Democratic Republic of Congo5·38 (1·4–21·2)Guinea-Bissau1·87 (1·1–3·3)Gambia3·42 (1·9–6·2)References for these studies are available from the authors. Open table in a new tab In a study from Bangladesh, children who received DTP/BCG after the age of measles vaccine administration had around threefold higher mortality than unvaccinated children.5Breiman RF Streatfield PK Phelan M Shifa N Rashi M Yunus M Effect of infant immunization on childhood mortality in rural Bangladesh: analysis of health and demographic surveillance data.Lancet. 2004; 364: 2204-2211Summary Full Text Full Text PDF PubMed Scopus (115) Google Scholar These observations have not been contradicted. If they are true, the drive to boost the DTP3 coverage could lead to increased child mortality. Current policy is based on the assumption that receiving three DTP vaccines is associated with decreased child mortality. It should be a major priority to determine whether this assumption is correct.We declare that we have no conflicts of interest. Stephen Lim and colleagues1Lim SS Stein DB Charrow A Murray CJ Tracking progress towards universal childhood immunisation and the impact of global initiatives: a systematic analysis of three-dose diphtheria, tetanus, and pertussis immunisation coverage.Lancet. 2008; 372: 2031-2046Summary Full Text Full Text PDF PubMed Scopus (210) Google Scholar scrutinise coverage with the third dose of diphtheria-tetanus-pertussis vaccine (DTP3) in 193 countries. With donor emphasis on DTP3 coverage, it is not surprising that the national estimates might be inflated. Still, there is little doubt that DTP3 coverage has increased in recent decades. But maybe we should be more concerned about the health implications of this trend than about the accuracy of the estimate. From a public health perspective, the fact that DTP3 coverage is now higher than measles vaccine coverage in most African countries is of questionable value. Numerous studies have shown that measles vaccine is beneficial for child survival,2Aaby P Samb B Simondon F Coll Seck AM Knudsen K Whittle H Non-specific beneficial effect of measles immunisation: analysis of mortality studies from developing countries.BMJ. 1995; 311: 481-485Crossref PubMed Scopus (257) Google Scholar but there are conflicting data about the effect of DTP. DTP has frequently been associated with increased mortality in situations with herd immunity.3Aaby P Benn CS Nielsen J Lisse IM Rodrigues A Jensen H Estimating the effect of DTP vaccination on mortality in observational studies with incomplete vaccination data.Trop Med Int Health. 2007; 12: 15-24Crossref PubMed Google Scholar Furthermore, as a result of the drive to increase the DTP3 coverage, more children receive DTP simultaneously with or after measles vaccine. We have found consistently that DTP given simultaneously with measles vaccine (table) or after it4Aaby P Jensen H Samb B et al.Differences in female-male mortality after high-titre measles vaccine and association with subsequent vaccination with diphtheria-tetanus-pertussis and inactivated poliovirus: reanalysis of West African studies.Lancet. 2003; 361: 2183-2188Summary Full Text Full Text PDF PubMed Scopus (172) Google Scholar is associated with increased mortality compared with having measles vaccine alone as the most recent vaccine. References for these studies are available from the authors. In a study from Bangladesh, children who received DTP/BCG after the age of measles vaccine administration had around threefold higher mortality than unvaccinated children.5Breiman RF Streatfield PK Phelan M Shifa N Rashi M Yunus M Effect of infant immunization on childhood mortality in rural Bangladesh: analysis of health and demographic surveillance data.Lancet. 2004; 364: 2204-2211Summary Full Text Full Text PDF PubMed Scopus (115) Google Scholar These observations have not been contradicted. If they are true, the drive to boost the DTP3 coverage could lead to increased child mortality. Current policy is based on the assumption that receiving three DTP vaccines is associated with decreased child mortality. It should be a major priority to determine whether this assumption is correct. We declare that we have no conflicts of interest.