Xavier Bosch-Capblanch
Meike-Kathrin Zuske
Christian Auer
Publication Date
June 7, 2017

Swiss Tropical and Public Health Institute; and Universität Basel (Bosch-Capblanch, Zuske, Auer)

Through an overview of systematic reviews (SRs) in the area of vaccination, this study aims to describe how, globally, research on the effects of interventions on vaccination coverage has looked specifically at vulnerable populations, and, in particular, which research exists on interventions to reduce inequity gaps. One of the six guiding principles in the Global Vaccine Action Plan (GVAP) is equity: "equitable access to immunisation is a core component of the right to health." The main finding of the study is that, although research on vulnerable populations as a subgroup is abundant, it fails to report on the interventions that will actually reduce inequities and consider how redistribution of health care resources could shrink the gap between the privileged and most vulnerable groups, including minorities.

The researchers carried out an overview of SRs that explicitly explored the effects of interventions to improve vaccination in any context, for any vaccine, and in any language. They followed standard research synthesis methods to systematically search for SRs, assess them for inclusion, and extract relevant data, particularly on vaccination- related outcomes. To gather evidence on equity issues addressed in the SRs, they used the PROGRESS-plus framework, which stands for: Place of residence; Race/ethnicity, Occupation; Gender; Religion; Education; Socioeconomic status (SES); Social capital; "plus" age, disability, and sexual orientation. In the end, 54 SRs, published between 1994 and 2014, were included in the analysis.

The quality of SRs was generally poor, with less than half complying with most of the quality criteria. Reported vaccines included, by order of frequency, influenza and Expanded Programme on Immunisation (EPI) vaccines. The types of interventions more frequently reported were related to vaccination delivery strategies, financial support, and information, education, and communication (IEC). Most of the SRs suggested effects favouring intervention groups as opposed to comparison groups. The most frequently reported equity attribute was "place of residence", and the least reported equity attributes were sexual orientation and religion. Very few estimates of effects actually measured differences or changes between groups having those attributes, and all of them referred to the place of residence. No data was found about reducing equity gaps for vulnerable groups or minorities, or attributes such as sexual orientation, education, or specific religious groups.

The researchers note that studies out of low- and middle-income countries (LMICs), where much of the burden of disease is, and where vaccination coverage rates are lower, are less abundant and not particularly focused on equity. It is striking for example, that despite consistent evidence that the level of education of caregivers is negatively related to vaccination status in LMICs, education is one of the least addressed equity factors the researchers could find. One explanation for this could be the ethical dilemmas of carrying out comparative studies in which one control or comparison group would not benefit from a basic educational intervention, such as literacy education.

Inequity is described here as a matter of justice. "Targeted interventions may have an impact on improving the health of vulnerable populations...; yet, this does not necessarily imply reducing differences and improving equity. In most of the evidence we retrieved, interventions had vulnerable groups as participants, but they did not seem to be specifically designed to address the gaps in health and health care between disadvantaged and privileged groups, as reported by authors."

In conclusion: "While the amount of descriptive research on the status of the most vulnerable population is overwhelming and there is also abundant research on interventions to improve vaccination outcomes, our overview identified two gaps: (a) research on specific minority groups (e.g. religious or groups defined by sexual orientation) and (b) research on what works, not only to improve health outcomes in general, but to close the inequity gaps between the privileged and the vulnerable populations: how to effectively redistribute health among the different layers or society. This is essential to inform national and international choices which affect the access of the most vulnerable (being they majorities or minorities) to the health care that others already enjoy. Research and policy, if wishing to remain relevant, should mirror the unbearable suffering of disadvantaged human beings by prioritising the production of robust evidence on what affects them, no matter how many they are or where they live."


International Journal for Equity in Health (2017) 16:95 DOI 10.1186/s12939-017-0587-x - sourced from: TechNet-21, December 5 2017. Image credit: Gavi