Proportionate Target Population Estimates Used by National Immunization Programmes in Sub-Saharan Africa and Comparison with Values from an External Source

Background: In order to effectively plan the delivery of immunization services, manage stock and supply levels and target interventions, national immunization programmes (NIP) must have an estimate of the target population they serve. To overcome challenges with target population estimation, some NIPs apply “rule-of-thumb” conversion factors to total population estimates. We compare these proportionate target population values with those from an external source. Methods: Using data reported by national immunization programmes in sub-Saharan Africa, we computed the proportionate target population as the number of births, surviving infants and children under 5 years of age, respectively, as a proportion of the total population size. We compared these values with those estimates computed from United Nations Population Division (UNPD) data. We then recomputed NIP target population sizes using the proportionate target population values from the UNPD applied to the total population size reported by NIP. Results: Data were available from 47 sub-Saharan Africa countries. Births as a proportion of the total population were greater within reports from NIP (median, 0.0400;IQR: 0.350 - 0.0437) compared to values from UNPD estimates (median, 0.0364;IQR: 0.0332 - 0.0406). Similar patterns were observed for surviving infants (median: NIP, 0.0360;UNPD, 0.0337) and children under 5 years of age (median: NIP, 0.1735;UNPD, 0.1594). The percent difference in proportionate target population ratios between reports from NIPs and the UNPD was >10% in 23 countries for births, in 18 countries for surviving infants, in 15 countries for children under 5 years of age. After re-computing target populations using UNPD proportionate target population values applied to NIP reported total population, recomputed administrative coverage levels for the third dose of DTP containing vaccine were higher in 32 of the 47 countries compared to reported administrative coverage levels. Conclusion: Because childhood immunization-related target populations are among the more difficult ones to accurately estimate and project, immunization programmes in sub-Saharan Africa are encouraged to include a critical assessment of the target population values, in conjunction with their national statistics system, as part of the on-going programme monitoring process.

Avoiding the Will O’ the Wisp: Challenges in Measuring High Levels of Immunization Coverage with Precision

There have been tremendous improvements in immunization coverage since the Expanded Programme on Immunization was launched. We highlight inherent challenges in measuring immunization coverage with precision as coverage levels increase due to the sensitivity of coverage to the accuracy of target population estimates. In fact, when comparing across groups at high levels of coverage, error in target population estimates can obscure differences in immunization coverage.

A Comparison of National Immunization Programme Target Population Estimates with Data from an Independent Source and Differences in Computed Coverage Levels for the Third Dose of DTP Containing Vaccine

Background: Comparison of target populations for immunization used by national immunization programmes with independent sources can be useful for identifying irregular patterns. Similarly, understanding differences in computed coverage levels that result from changes in target population estimates can be important. Methods: Using data reported annually by national immunization programmes to WHO and UNICEF, we compared the national number of births and surviving infants with estimates reported by the United Nations Population Division (UNPD). We also re-computed and compared coverage levels for the third dose of DTP containing vaccine (DTP3) using the nationally reported number of children vaccinated with DTP3 (the numerator) and the nationally reported number of children in the target population (the denominator) and compared this value with DTP3 coverage computed using the nationally reported number of children vaccinated and the UNPD estimate of the national number of surviving infants as an independent denominator. Results: We observed differences in the number of births and surviving infants reported by national immunization programmes compared with those estimated by the UNPD. Year-to-year changes in the number of births and surviving infants reported by national immunization programmes often exceeded those estimated by the UNPD. The re-computed administrative coverage levels for DTP3 using a nationally reported target population tended to be higher on average than those re-computed using the UNPD target population estimates. Conclusion: Target population estimates are a challenge for immunization programmes, and comparison to independent sources can be useful. There is increasing need to trace and better understand the processes and conditions affecting the enumeration and recording of the number of children in the target population for immunization services and the number of children vaccinated while recognizing that the challenge to do so is greater in some locations than others.

Reported National Level Stock-Outs of Home-Based Records—A Quiet Problem for Immunization Programmes That Needs Attention

Home-based records (HBRs) are an important tool for recording and communicating within primary healthcare service delivery. Unfortunately, HBRs are currently unable to fulfil their intended purpose in many communities either because the HBR is not functionally well-designed to serve its objectives, not made available, not fully adopted and/or not appropriately utilized by caregivers and/or health workers. This brief report describes the occurrence of nationally reported HBR stock-outs and HBR financing patterns during 2014 and 2015 across 195 countries reporting immunization system performance data to the World Health Organization and United Nations Children’s Fund. National level HBR stock-outs were reported by 19 and 22 countries during 2014 and 2015, respectively, with eleven countries reporting stock-outs during both 2014 and 2015. During 2015, 12 of the 22 countries reporting HBR stock-outs were from the African Region and two-thirds of the countries were Gavi-eligible. Information on HBR stock-outs was either not available or not reported by 66 countries (19 were Gavi-eligible) for 2014 and 53 (11 were Gavi-eligible) countries for 2015. Among the 22 countries reporting HBR stock-outs in 2015, 12 (54%) countries reported a single HBR financing source, and nine (41%) countries reported more than one source for HBR financing. The occurrence of HBR stock-outs remains a concern, particularly in Gavi-eligible countries introducing new vaccines where dedicated funding is received for revising and printing new recording tools, including HBRs. Additional attention is needed to understand the root causes for stock-outs and identify solutions to ensure a well-designed, durable HBR is readily available in the right quantity, in the right place at the right time in all countries.

Non-Participation in Child Health Days or Routine Immunization Services among Children under 5 Years of Age—Somaliland 2012

Background: After two decades of conflict, Somalia remains a fragile state where large scale displacement and inadequate access to functioning health services have left children vulnerable to morbidity and mortality from vaccine preventable disease. Children residing in the autonomous zone of Somaliland are similarly vulnerable to poor access to health care services. Following the conduct of a UNICEF-supported Multiple Indicator Cluster Survey in Somaliland during 2011 which captured information on immunization system performance, a survey was conducted to better understand the reasons for non-vaccination among children in Somaliland. Methods: The Somaliland Routine Immunization Non-Participation Survey (RINPS) was conducted in November 2012 to better understand the reasons for non-participation in both Child Health Days (CHDs) and Routine Immunization Services (RIS). RINPS was a cross-sectional household survey which used a two-stage sample design in order to obtain a representative sample of children 0 - 59 months of age residing in Somaliland. Thirty clusters were randomly selected from the 303 clusters for participation in the 2011 Somaliland MICS. A total of 867 children aged 0 - 59 months were identified and included in the analysis (overall response rate, 96%). Findings: Caregivers lacked motivation to take their children to CHDs and for RIS and lacked information about why children need immunization. Routine vaccination or CHD cards were available for few children at the time of the survey. Almost one-fifth of children aged 0 - 59 months in Somaliland had not received at least one dose of vaccine for DTP, polio or measles vaccine from either CHD or RIS. Conclusion: Child Health Days have a role in at least some area of Somaliland to expand the reach of immunization services. The availability and delivery of sustainable routine immunization services need to be strengthened in Somaliland with a strong social mobilization program to raise awareness about the importance of routine immunization.