Comparison of inflation of third dose diphtheria tetanus pertussis (DTP3) administrative coverage to other vaccine antigens

Defining the Zero Dose Child: A Comparative Analysis of Two Approaches and Their Impact on Assessing the Zero Dose Burden and Vulnerability Profiles across 82 Low- and Middle-Income Countries

While there is a coordinated effort around reaching zero dose children and closing existing equity gaps in immunization delivery, it is important that there is agreement and clarity around how 'zero dose status' is defined and what is gained and lost by using different indicators for zero dose status. There are two popular approaches used in research, program design, and advocacy to define zero dose status: one uses a single vaccine to serve as a proxy for zero dose status, while another uses a subset of vaccines to identify children who have missed all routine vaccines. We provide a global analysis utilizing the most recent publicly available DHS and MICS data from 2010 to 2020 to compare the number, proportion, and profile of children aged 12 to 23 months who are 'penta-zero dose' (have not received the pentavalent vaccine), 'truly' zero dose (have not received any dose of BCG, polio, pentavalent, or measles vaccines), and 'misclassified' zero dose children (those who are penta-zero dose but have received at least one other vaccine). Our analysis includes 194,829 observations from 82 low- and middle-income countries. Globally, 14.2% of children are penta-zero dose and 7.5% are truly zero dose, suggesting that 46.5% of penta-zero dose children have had at least one contact with the immunization system. While there are similarities in the profile of children that are penta-zero dose and truly zero dose, there are key differences between the proportion of key characteristics among truly zero dose and misclassified zero dose children, including access to maternal and child health services. By understanding the extent of the connection zero dose children may have with the health and immunization system and contrasting it with how much the use of a more feasible definition of zero dose may underestimate the level of vulnerability in the zero dose population, we provide insights that can help immunization programs design strategies that better target the most disadvantaged populations. If the vulnerability profiles of the truly zero dose children are qualitatively different from that of the penta-zero dose children, then failing to distinguish the truly zero dose populations, and how to optimally reach them, may lead to the development of misguided or inefficient strategies for vaccinating the most disadvantaged population of children.

Coverage, inequity and predictors of hepatitis B birth vaccination in Myanmar from 2011-2016: results from a national survey

Background

Hepatitis B virus birth dose (HepB-BD) vaccination is recommended to reduce mother to infant transmission. We evaluated the HepB-BD status of women who gave birth between 2011 and 2016 (N = 3,583) using the 2015–2016 Myanmar Demographic and Health Survey.

Methods

Frequency distributions of HepB-BD vaccination across maternal and health system factors, concentration indices, and logistic regression models were used to estimate coverage, inequity, and factors associated with vaccination.

Results

The majority of participants were younger than 30 years of age, lived in rural areas, and were multiparous. Almost all received antenatal care (ANC), but only 43% received recommended ANC services, and 60% gave birth at home. The overall HepB-BD coverage rate was 26%. Vaccination coverage was higher in urban areas and was inequitably concentrated among children of more educated and wealthier women. HepB-BD coverage was also positively associated with receipt of ANC at non-governmental facilities, and delivery at a facility, skilled provider at birth and Cesarean delivery. After adjusting for sociodemographic and health system factors, receipt of the HepB-BD was positively associated with weekly media exposure, receipt of recommended ANC, and Cesarean delivery, and inversely associated with home delivery.

Conclusions

Both socioeconomic and health systems factors influenced suboptimal and inequitable vaccination coverage. Improved access to quality ANC and delivery services may increase HepB-BD coverage although targeted approaches to reach home births are likely required to achieve national goals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-07902-w.

Improving the quality and use of immunization and surveillance data: Summary report of the Working Group of the Strategic Advisory Group of Experts on Immunization

Concerns about the quality and use of immunization and vaccine-preventable disease (VPD) surveillance data have been highlighted on the global agenda for over two decades. In August 2017, the Strategic Advisory Group of Experts (SAGE) established a Working Group (WG) onthe Quality and Use of Global Immunization and Surveillance Data to review the current status and evidence to make recommendations, which were presented to SAGE in October 2019. The WG synthesized evidence from landscape analyses, literature reviews, country case-studies, a data triangulation analysis, as well as surveys of experts. Data quality (DQ) was defined as data that are accurate, precise, relevant, complete, and timely enough for the intended purpose (fit-for-purpose), and data use as the degree to which data are actually used for defined purposes, e.g., immunization programme management, performance monitoring, decision-making. The WG outlined roles and responsibilities for immunization and surveillance DQ and use by programme level. The WG found that while DQ is dependent on quality data collection at health facilities, many interventions have targeted national and subnational levels, or have focused on new technologies, rather than the people and enabling environments required for functional information systems. The WG concluded that sustainable improvements in immunization and surveillance DQ and use will require efforts across the health system - governance, people, tools, and processes, including use of data for continuous quality improvement (CQI) - and that the approaches need to be context-specific, country-owned and driven from the frontline up. At the country level, major efforts are needed to: (1) embed monitoring DQ and use alongside monitoring of immunization and surveillance performance, (2) increase workforce capacity and capability for DQ and use, starting at the facility level, (3) improve the accuracy of immunization programme targets (denominators), (4) enhance use of existing data for tailored programme action (e.g., immunization programme planning, management and policy-change), (5) adopt a data-driven CQI approach as part of health system strengthening, (6) strengthen governance around piloting and implementation of new information and communication technology tools, and (7) improve data sharing and knowledge management across areas and organizations for improved transparency and efficiency. Global and regional partners are requested to support countries in adopting relevant recommendations for their setting and to continue strengthening the reporting and monitoring of immunization and VPD surveillance data through processes periodic needs assessment and revision processes. This summary of the WG's findings and recommendations can support "data-guided" implementation of the new Immunization Agenda 2030.

Impact of state weights on national vaccination coverage estimates from household surveys in Nigeria

National vaccination coverage estimates from household surveys are widely used in monitoring and planning of immunization programs. In Nigeria, survey-reported national coverage estimates have shown large fluctuations in the past few years. In this paper, we examine the impact of state-level survey weighting on Nigeria's national vaccination coverage estimation. In particular, we focus three vaccination-related outcomes among children aged 12-23 months: the coverage of the third dose of diphtheria, pertussis, and tetanus vaccine (DPT3); the coverage of the first dose of measles-containing vaccine (MCV1); and the availability rate of home-based vaccination record (HBR). We compare the sample selection and weight assignment of three major survey programs in Nigeria, and show that considerable portions of the changes in survey-reported national coverage estimates can be explained by shifts in state-level weights. Our analysis demonstrates the importance of state weighting method in estimating aggregated national coverage figures and provides important context for interpreting changes in coverage estimates between surveys in the future.

Has Gavi lived up to its promise? Quasi-experimental evidence on country immunisation rates and child mortality

Introduction

Gavi, the Vaccine Alliance, was set up in 2000 to improve access to vaccines for children living in the poorest countries. Funding has increased significantly over time, with Gavi disbursements reaching US $1.58 billion in 2015. We assess whether Gavi’s funding programmes have indeed increased immunisation coverage in 51 recipient countries for two key vaccines for 12–23 month olds: combined diphtheria, pertussis and tetanus (DPT) and measles. Additionally, we look at effects on infant and child mortality.

Methods

Taking a difference-in-differences quasi-experimental approach to observational data, we estimate the impact of Gavi eligibility on immunisation coverage and mortality rates over time, using WHO/UNICEF figures covering 1995–2016. We control for economy size and population of each country as well as running a suite of robustness checks and sensitivity tests.

Results

We find large and significant positive effects from Gavi’s funding programmes: on average a 12.02 percentage point increase in DPT immunisation coverage (95% CI 6.56 to 17.49) and an 8.81 percentage point increase in measles immunisation coverage (95% CI 3.58 to 14.04) over the period to 2016. Our estimates show Gavi support also induced 6.22 fewer infant deaths (95% CI −10.47 to −1.97) and 12.23 fewer under-five deaths (95% CI −19.66 to −4.79) per 1000 live births.

Conclusion

Our findings provide evidence that Gavi has had a substantial impact on the fight against communicable diseases for improved population and child health in lower-income countries. In this case, the health policy to verticalise aid—specifically development assistance for health—via a specialised global fund has had positive outcomes.

Defining & assessing the quality, usability, and utilization of immunization data

Background

High quality data are needed for decision-making at all levels of the public health system, from guiding public health activities at the local level, to informing national policy development, to monitoring the impact of global initiatives. Although a number of approaches have been developed to evaluate the underlying quality of routinely collected vaccination administrative data, there remains a lack of consensus around how data quality is best defined or measured.

Discussion

We present a definitional framework that is intended to disentangle many of the elements that have confused discussions of vaccination data quality to date. The framework describes immunization data in terms of three key characteristics: data quality, data usability, and data utilization. The framework also offers concrete suggestions for a specific set of indicators that could be used to better understand immunization those key characteristics, including Trueness, Concurrence, Relevancy, Efficiency, Completeness, Timeliness, Integrity, Consistency, and Utilization.

Conclusion

Being deliberate about the choice of indicators; being clear on their definitions, limitations, and methods of measurement; and describing how those indicators work together to give a more comprehensive and practical understanding of immunization data quality, usability, and use, should yield more informed, and therefore better, programmatic decision-making.

Coverage and timeliness of vaccination and the validity of routine estimates: Insights from a vaccine registry in Kenya

BACKGROUND

The benefits of childhood vaccines are critically dependent on vaccination coverage. We used a vaccine registry (as gold standard) in Kenya to quantify errors in routine coverage methods (surveys and administrative reports), to estimate the magnitude of survivor bias, contrast coverage with timeliness and use both measures to estimate population immunity.

METHODS

Vaccination records of children in the Kilifi Health and Demographic Surveillance System (KHDSS), Kenya were combined with births, deaths, migration and residence data from 2010 to 17. Using inverse survival curves, we estimated up-to-date and age-appropriate vaccination coverage, calculated mean vaccination coverage in infancy as the area under the inverse survival curves, and estimated the proportion of fully immunised children (FIC). Results were compared with published coverage estimates. Risk factors for vaccination were assessed using Cox regression models.

RESULTS

We analysed data for 49,090 infants and 48,025 children aged 12-23 months in 6 birth cohorts and 6 cross-sectional surveys respectively, and found 2nd year of life surveys overestimated coverage by 2% compared to birth cohorts. Compared to mean coverage in infants, static coverage at 12 months was exaggerated by 7-8% for third doses of oral polio, pentavalent (Penta3) and pneumococcal conjugate vaccines, and by 24% for the measles vaccine. Surveys and administrative coverage also underestimated the proportion of the fully immunised child by 10-14%. For BCG, Penta3 and measles, timeliness was 23-44% higher in children born in a health facility but 20-37% lower in those who first attended during vaccine stock outs.

CONCLUSIONS

Standard coverage surveys in 12-23 month old children overestimate protection by ignoring timeliness, and survivor and recall biases. Where delayed vaccination is common, up-to-date coverage will give biased estimates of population immunity. Surveys and administrative methods also underestimate FIC prevalence. Better measurement of coverage and more sophisticated analyses are required to control vaccine preventable diseases.