Despite the introduction of an increasing number of vaccines to the Expanded Programme on Immunisation (EPI), and huge government and development partners’ investments, many children globally continue to go unvaccinated by their first birthday or never complete the recommended schedule. In sub-Saharan Africa, particularly in West Africa, vaccination coverage rates are lower than in other regions of the world, despite having the highest burden of vaccine preventable diseases. Furthermore, entrenched intra-country equity gaps in immunisation systems, a situation characterised by marked differences in access and utilisation of immunisation services across several social and economic determinants of health, have been shown to exist in West Africa.
To understand these coverage and equity gaps in immunization systems, a team of researchers assessed and compared the vaccination coverage, dropout, and equity gaps between 2000 and 2017 across 15 West African countries whose regional alliance, the Economic Community of West African States (ECOWAS) promotes integration in all fields of activity, including the health of the constituting countries. The work was a collaboration between a team of researchers from the Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, the Vaccine Centre at the London School of Hygiene and Tropical Medicine and colleagues from the World Health Organization (WHO) Country Office for Nigeria.

This multi-country analysis focused on Benin, Burkina Faso, Cabo Verde, Cote d’ Ivoire, The Gambia, Ghana, Guinea, Guinea Bissau, Liberia, Mali, Niger, Nigeria, Senegal, Sierra Leone and Togo. The research, published in the https://gh.bmj.com/content/bmjgh/4/5/e001713.full.pdf, tracked access to childhood immunization (using BCG coverage), overall vaccination coverage (using the third dose of Diphtheria Tetanus and Pertussis containing vaccine; DTP3), and the proportion of children who drop out between DTP1 and DTP3 against the WHO recommended coverage, and dropout benchmarks. Furthermore, the analysis unpacked these coverages and dropouts across 5 equity dimensions - a child’s place of residence, sex, family wealth, maternal education and regions within a country - to understand the inequalities in immunisation systems between the most advantaged and the most disadvantaged sub-populations of children in West Africa. The study integrated data from WHO/UNICEF Estimates of National Immunization Coverage (WUENIC), Multiple Indicator Cluster Survey (MICS), Demographic Health Surveys (DHS) and UN Population estimates for 2017.

The study found that between 2000 and 2009, West African countries made significant strides at increasing national immunisation coverages and retaining children who commenced vaccination in the immunisation systems. However, coverages have plateaued in most countries since 2009, after an initial rapid increase with sub-regional average weighted BCG/DTP3 coverage lagging significantly behind the WHO recommended vaccination coverage benchmarks. Guinea, Mali, and Nigeria consistently had the lowest coverage and the widest equity gaps in immunisation in West Africa, with inequalities in coverages and dropouts mostly related to poverty, low maternal education, and living in certain disadvantaged regions within a country. Cabo Verde, Burkina Faso and The Gambia can be considered as ‘outlier’ highly successful countries in West Africa, as they have consistently maintained BCG and DTP3 coverage above 90% since 2015, and dropout rate below 10% since 2005.

Dr Oghenebrume Wariri, first author of the study, Research Clinician at the MRC Unit The Gambia at LSHTM said, “Our study is the first of its kind in the West African sub-region whose strength lies in the fact that we were able to integrate multiple nationally-representative and publicly-available data sources to give an in-depth understanding of immunisation systems in the sub region. Overall, our analysis suggests that in the main, children who start vaccination only dropout minimally. The big problem in the sub region appears to be the children who are not reached at all by the immunization system and are thus, left behind’’.

Prof Beate Kampmann, Theme Leader for Vaccines and Immunity at the MRC Unit The Gambia at LSHTM and Director of the Vaccine Centre at LSHTM said, “This study shows that a lot has been achieved to bring lifesaving vaccines to children in West Africa, but more work clearly is needed in key places. We need to look carefully at stumbling blocks and these might be at very local levels. Averages are no longer good enough. We must work together with communities and health systems to reach every child, everywhere with lifesaving vaccines”.

Dr Terna Nomhwange, National Consultant, WHO Country Office for Nigeria and Co-Senior author of the paper said, “The findings from this paper is a clear call to action for all countries within the sub region to do more in ensuring the complete immunization of all children. The continuing outbreaks of vaccine preventable diseases MUST stop. Our efforts must focus not only on reaching children with vaccines, but retaining them within the immunization system to complete their vaccination schedule regardless of where their parents/caregivers reside, wealth or educational status’’.

The findings imply that West African countries with low vaccination coverages and wide equity gaps could strengthen their immunisation systems by adopting useful lessons and local solutions from their peers in the sub-region who have achieved and sustained the recommended WHO childhood vaccination targets on coverages and equity. Furthermore, continued government commitment and investment in the sub-region will be pivotal in reaching the children who are ‘left behind’, reducing equity gaps, and ensuring that hard-won gains are maintained especially with some Gavi-eligible countries scheduled for graduation from Gavi support in the coming years.