Table 1

Studies used in the analysis

Country/referenceSettingDesign and commentsNo. of childrenAge groupLength of follow-upInformation on unvaccinatedVaccinesOther vaccinations during follow-up
Studies of DTP administered after no prior vaccine and before MV: Guinea-Bissau
 DTP introduction42Rural area; first introduction of DTP. Few had received BCGIntroduction of DTP in 20 villages; unvaccinated were children who were travelling, too sick to get vaccinated and children examined on days when vaccines not available for logistic reasons. General and sex-specific mortality rates available.16572–8 months6 monthsVaccination provided by projectDTP, BCGThe proportion receiving additional doses of DTP during follow-up increased from 14% to 40% (average 28%) during project; the proportion receiving MV increased from 2% to 18% (average 11%).
Studies of DTP administered after BCG and before MV: Guinea-Bissau
 Routine vaccinations1RuralSurvey in 100 villages; first results from this study reported in Aaby et al.11 General mortality rates available.87520–13 months6 monthsVaccination cardBCG, DTP, MVAdditional vaccinations were provided during follow-up; 65%–71% vaccinated
 War26Urban population in rural areaSurvey before war, mortality during war. General and sex-specific mortality rates available14911–17 months3 months in warVaccination card before warBCG, DTP, MV42% of DTP-unvaccinated received DTP during follow-up—only 2% of MV-unvaccinated received MV
 Guinea-Bissau, Senegal twins28Female–male twin pairs from several studiesMortality until next vaccine. Only deaths by sex and vaccination status available.626 pairs0–17 monthsWithin 0–17 months of ageVaccination cardBCG, DTP, MVUnlikely since the co-twin would indicate whether other vaccinations had been received
 Hospital case death27Hospital mortalitySurvey at admission. Only deaths by sex and vaccination status available.20790–17 monthsAt hospitalVaccination cardBCG, DTP, MVVaccination status assessed at hospitalisation. No additional vaccinations at hospital
 Hospital-OPV43Hospital mortalitySurvey at admission, DTP missing in certain periods. Only deaths by sex and vaccination status available.7190–59 monthsAt hospitalVaccination cardDTP, OPVVaccination status assessed at hospitalisation. No additional vaccinations at hospital
 Trial of vitamin A supplementation (VAS) at birth52UrbanProspective community trial. General and sex-specific mortality rates available43450–8 months8 monthsBCG provided by project; Vaccinations from health centres, home visits, verbal autopsyBCG, DTPAll children who died at 0–1.5 months of age had BCG as most recent vaccination. Female–male MRR at 0–1.5 months has been taken to be indicative of the BCG effect. Children with DTP as most recent vaccination are unlikely to have received MV during follow-up as all MV in study area controlled by project
 Low birth weight cohort64 65UrbanProspective community trial with assessment of vaccination status at 2 and 6 months of age. General and sex-specific mortality rates available.18302–6 months4 monthsVaccination card seen at 2 and 6 monthsBCG, DTPVaccination status known for all children. Most unvaccinated children received DTP during follow-up
 Early MV trial3UrbanDTP3-vaccinated children randomised at 4.5 months of age to receive MV or maintain DTP3 as most recent vaccination. General and sex-specific mortality rates available.66484.5–9 months4.5 monthsAll vaccines documentedDTP3, MVNo vaccine until MV was due at 9 months of age since they had all received DTP3 before enrolment
Studies of DTP administered after BCG and before MV: studies from other countries
 Nigeria9RuralRandomised study of MV versus DTP. Only deaths by vaccination status available.5218 monthsVaccination provided by projectDTP, MVUnlikely
 Benin18RuralCase–control study of community deaths. Only deaths by vaccination status available.74 deaths + 230 controls0–35 monthsMaximum 3 yearsVaccination cardBCG, DTP, MVKnown from vaccination card
 Malawi53RuralRoutine monthly surveillance. General and sex-specific mortality rates available7670–17 monthsWithin 0–17 monthsVaccination cardBCG, DTP, MVWith monthly visits and control of health centre records unlikely that many vaccines have been missed; the study included the children seen at the monthly home visit for whom vaccination records are assumed to be complete
 Gambia31RuralNo individual vaccination information collected. Coverage for children <5 years known from two surveys.Vaccination cards of dead children collected at verbal autopsy.537 deaths under 5 years0–17 monthsWithin 0–17 monthsVaccination cards collected from dead childrenBCG, HBV, DTP, MVVaccination status known from vaccination card of children who died. All children who died at 5–8 months of age had DTP as most recent vaccination and nearly all children who died at 12–17 months had MV as most recent vaccination.
 Bangladesh54UrbanTrial: children hospitalised with diarrhoea received DTP1 at discharge and were randomised to VAS/placebo. DTP2 and DTP3 were provided during follow-up together with VAS/placebo. General and sex-specific mortality rates available.2001–12 months6 months after DTPVaccination provided by projectDTP
Studies of DTP administered after MV
 Guinea-Bissau5 6UrbanTrial of HTMV. General and sex-specific mortality rates available2424–8 months3–5 years of ageVaccination provided by projectDTP, IPV, MVMost vaccines were controlled by project
 Senegal7RuralTrial of HTMV. General and sex-specific mortality rates available15795 months3–5 years of ageVaccination provided by projectDTP-IPV, MVUnlikely that many vaccines have been given since project controlled all vaccinations in area
 Senegal23RuralRoutine use of HTMV. General and sex-specific mortality rates available9445–7 months3 years of ageVaccination provided by projectDTP-IPV, MVUnlikely that many vaccines have been given since project controlled all vaccinations in area
 Congo22UrbanTrial of HTMV. General and sex-specific mortality rates available1023Cohort 1: 3.5–9.5 months; cohort 2: 6 months30 monthsVaccination provided by projectDTP, MVAdditional DTP vaccinations unlikely to have been given since most had received DTP3 in cohort 2.
 Sudan22RuralTrial of HTMV. General and sex-specific mortality rates available5105 months31 monthsVaccination provided by projectDTP, MVLikely that additional DTP vaccinations might have been given to those missing DTP3
 Two-dose MV trial51UrbanStandard MV given at 6 months; control group received IPV. Both groups received MV at 9 months. General and sex-specific mortality rates available85116–9 monthsMostly 3–6 monthsVaccination provided by projectIPV, DTP, MVThose missing DTP3 likely to have received DTP during follow-up. Control children unlikely to have received MV before 9 months of age as all MV administered by project.
 Guinea-Bissau57UrbanSurvey at admission; only children with MV. Only deaths by sex and vaccination status available.7796–17 monthsAt hospitalVaccination cardDTP, MVNo additional vaccinations at hospital
 Ghana74RuralTrial of VAS; vaccination status assessed at enrolment. General and sex-specific mortality rates available.11 7226–60 months2 yearsVaccination cardDTP, MVMost vaccines given out of sequence. Analysed for DTP after MV
 Guinea-Bissau78UrbanTrial of vitamin A with MV4559–36 months27 monthsVaccination cardDTP, MVThose missing DTP3 likely to have received DTP during follow-up
Morbidity studies
 Guinea-Bissau: Morbidity55 56Urban, cohort followed each weekIncidence of cryptosporidium and rotavirus2000–23 months6 months or to 24 months of ageVaccination cardBCG, DTP, MVPerfect information on vaccination since only children with card seen after episode has been used.
 Guinea-Bissau75UrbanRisk of hospitalisations for measles infection12 1076–59 monthsVaccination cardBCG, DTP, MV

  • DTP, diphtheria–tetanus–pertussis; HBV, hepatitis B virus; HTMV, high-titre measles vaccine; MV, measles vaccine; OPV, oral polio vaccine.