ArticlesTracking progress towards universal childhood immunisation and the impact of global initiatives: a systematic analysis of three-dose diphtheria, tetanus, and pertussis immunisation coverage
Introduction
In many countries, vaccine-preventable diseases remain major causes of child mortality.1 Delivery of childhood immunisations is an essential dimension of health systems and is included as an indicator for Millennium Development Goal 4. Overall performance of immunisation programmes has most often been tracked with the coverage of three doses of diphtheria, tetanus, and pertussis vaccine (DTP3).
Over the past 30 years, substantial resources have been invested through global initiatives to scale up immunisation coverage.2, 3 In 1974, WHO launched the Expanded Programme on Immunisation (EPI).4 After this programme, in 1977, a global goal for universal child immunisation against the six basic antigens (measles, poliomyelitis, diphtheria, pertussis, tetanus, and tuberculosis) was articulated at the World Health Assembly.4 In 1984, UNICEF in partnership with others launched the Universal Childhood Immunisation (UCI) by 1990 initiative, defined as 80% immunisation coverage.2 UCI mobilised substantial funds and support for delivery of immunisation services and, in 1990, UNICEF declared that UCI's target had been achieved.5
In the 1990s, estimates suggested that improvements in immunisation coverage were stagnating or falling.2, 6, 7 In response, the Global Alliance on Vaccines and Immunisations (GAVI), a public–private partnership that aims to increase coverage of basic vaccines and to accelerate the introduction of new vaccines in low-income and middle-income countries, was launched in 1999. Although GAVI provides a range of support, immunisation services support (ISS) is the funding that aims to increase coverage of basic vaccines such as DTP3. ISS is provided in response to country proposals and represents flexible cash that countries can use to improve immunisation performance.8
ISS payments are performance-based, with funds disbursed in proportion to the number of additional children less than 1 year of age targeted or reported to receive DTP3. Payments are divided between two phases: an investment phase (the first 2 years after a country's proposal has been approved) and a reward phase (the third year and onwards after approval).8 During the investment phase, US$20 is disbursed per additional child targeted by the country to receive DTP3 in the first year following approval of GAVI support. The baseline for determination of the additional number is the number of children receiving DTP3 in the year before the approval of ISS. In the reward phase, GAVI disburses $20 per additional child reported by countries to receive DTP3, compared with the target set during the investment phase or the number of children receiving DTP3 in the previous year if this number is higher.
The number of additional children receiving DTP3 is based on official reports from countries to WHO and UNICEF. These reports are largely but not exclusively based on administrative data from health-service-provider registries. In recognition of the weakness of administrative data systems and the potential for ISS to induce incentives for over-reporting, GAVI requires countries to pass a data quality audit (DQA) of their administrative data system to be eligible for reward payments.8, 9 DQAs are used to assess the accuracy of reports from health centres to districts and nationally on the number of additional children immunised with DTP3 by comparing this number against a re-count of paper records in health centres.9
Sample surveys are the other main source of data on immunisation coverage. These include standardised multicountry surveys, such as the demographic and health surveys (DHS), as well as country-specific surveys, such as the EPI 30-cluster by seven household surveys. Using both officially reported data and survey data, WHO and UNICEF jointly publish estimates of national and global DTP3 immunisation coverage.10, 11, 12 WHO and UNICEF estimates aim to reconcile differences between reported and survey data; however, their estimation is not undertaken in a reproducible way and nor do they include an estimation of uncertainty for the measurement of coverage.
There are several lingering concerns about the measurement of coverage. The quality of administrative data on immunisation coverage remains suspect due to problems with measurement,13 as well as the potential for target-oriented initiatives such as UCI2, 14, 15 and performance-based payment systems such as GAVI's ISS2, 7 to encourage health-service providers to over-report coverage. A previous analysis16 did not detect an effect of GAVI ISS on over-reporting, measured as the difference between officially reported and survey-based coverage; however, new data are now available to assess this effect in a larger number of countries.
In this study we seek to address these concerns by using all available data to systematically assess the survey-based trend in DTP3 crude coverage with uncertainty intervals during 1986–2006; and whether global health initiatives, such as UCI and GAVI ISS, lead to over-reporting of DTP3 immunisation coverage.
Section snippets
Data and definitions
We did a systematic search for data to estimate the coverage of DTP3 immunisation during 1980–2006. Available data fall into five categories: first 225 standardised multicountry surveys for which the microdata (unit-record data) are in the public domain; second, 78 standardised multicountry surveys for which results and sample size are reported but microdata were not available; third, 142 national surveys that measured immunisation coverage reported in the WHO and UNICEF vaccine coverage
Results
We provide DTP3 crude coverage estimates from analysed survey, reported survey (with and without sample sizes), and administrative data for 193 countries in webappendix 5. Figure 1 shows twelve examples of DTP3 crude coverage estimates from surveys, administrative data as well as countries' official estimates reported to WHO. These examples are intended to emphasise the importance of country by country assessment and to highlight patterns in the data; they are not intended to be representative
Discussion
Our systematic analysis shows that the crude coverage of DTP3 immunisation based on surveys has not progressed to the level suggested by countries' official reports or the WHO and UNICEF estimates. Furthermore, the way in which improvements in coverage have been achieved is far more gradual than suggested by officially reported estimates, or the WHO and UNICEF estimates. This gradual improvement probably indicates the investments and time needed to build the necessary infrastructure such as
References (60)
- et al.
Shifts in global immunisation goals (1984–2004): unfinished agendas and mixed results
Soc Sci Med
(2005) - et al.
GAVI, the first steps: lessons for the Global Fund
Lancet
(2002) - et al.
Validity of reported vaccination coverage in 45 countries
Lancet
(2003) - et al.
Effect of the Global Alliance for Vaccines and Immunisation on diphtheria, tetanus, and pertussis vaccine coverage: an independent assessment
Lancet
(2006) - et al.
Can we achieve Millennium Development Goal 4? New analysis of country trends and forecasts of under-5 mortality to 2015
Lancet
(2007) - et al.
Estimates of HIV-1 prevalence from national population-based surveys as a new gold standard
Lancet
(2003) - et al.
Increasing the accuracy of the Expanded Programme on Immunization's cluster survey design
Ann Epidemiol
(1994) - et al.
The accuracy of mothers' reports of child vaccination: evidence from rural Egypt
Soc Sci Med
(1998) - et al.
Another look at the instrumental variable estimation of error-components models
J Economet
(1995) - et al.
Initial conditions and moment restrictions in dynamic panel data models
J Economet
(1998)
Health workers and vaccination coverage in developing countries: an econometric analysis
Lancet
National serosurvey of poliovirus immunity in Australia, 1996–99
Aust N Z J Public Health
Access, utilization, quality, and effective coverage: an integrated conceptual framework and measurement strategy
Soc Sci Med
Evaluation of a measles vaccine campaign in Ethiopia using oral-fluid antibody surveys
Vaccine
Global burden of disease and risk factors
Global development goals: the United Nations experience
J Hum Dev
Expanded programme on immunization
World Health Stat Q
Vaccination in the 21st century—new funds, new strategies?
Trop Med Int Health
New products into old systems. The global alliance for vaccines and immunization (GAVI) from a country perspective
Immunisation services support (ISS)
The immunization data quality audit: verifying the quality and consistency of immunization monitoring systems
Bull World Health Organ
Immunization summary: the 2007 edition
WHO UNICEF review of national immunization coverage, 1980–2007
Country reports. WHO-UNICEF estimates on immunization coverage 1980–2006. UNICEF Statistics
Assessing immunization data quality from routine reports in Mozambique
BMC Public Health
The quality of immunization data from routine primary health care reports: a case from Nepal
Health Policy Plan
WHO/UNICEF Joint Reporting Process
Optimal sample sizes for two-stage cluster sampling in demographic and health surveys. DHS working papers, series number 30
An analysis of sampling design and sampling errors of the demographic and health surveys. DHS analytic reports number 3
Evaluation of bias in HIV seroprevalence estimates from national household surveys
Sex Transm Infect
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