The Impact of Public Financing, Economic Growth, and Corruption on Immunization Performance: Evidence from 37 Sub-Saharan African Countries

Immunization is a vital public health intervention that has saved countless lives by preventing and controlling the spread of infectious diseases ¹. It is a global health and development success story, owing to millions of lives saved every year, by reducing the risk of preventable diseases and building the body’s natural defenses ². Vaccines against preventable disease can now prevent over 20 life-threatening diseases, thereby contributing to lowering the burden of morbidity and mortality associated with vaccine-preventable diseases (VPDs) by 3.5-5 million deaths every year ³. To this end, children and vulnerable groups of all ages are now living longer and healthier lives thanks to the efficacy of vaccines ^{3, 4}. This is why the World Health Organization (WHO) considers vaccination to be a key component of universal healthcare and a fundamental human right.

In sub-Saharan Africa (SSA), where many countries continue to face high burdens of vaccine-preventable diseases, immunization programs have been a priority for both the governments and international organizations such as the World Health Organization (WHO), Gavi, the Vaccine Alliance, the Agence de Medicine Preventive (AMP) and others. Gavi has played a particularly instrumental role in many of the milestones achieved in the SSA by providing support to eligible countries to strengthen their immunization systems and increase access to vaccines, with a particular focus on low-income countries. Since its inception, Gavi has collaborated with over 40 African countries, leading to the introduction of nine new vaccines into the national routine immunization (RI) schedules, reaching 364 million children and disbursing over US$5.7 billion to Gavi-supported African countries. This has helped avert over 8.9 million child deaths ^{5, 6}. In addition to childhood immunization, intervention for adolescents have also been implemented. Gavi has supported over 13 SSA countries to introduce the Human Papillomavirus (HPV) vaccine, which is the primary cause of cervical cancer, and around 6 million adolescent girls between aged 9-15 in Africa were vaccinated against HPV in 2020 ⁶.

Despite the progress made in expanding access to vaccines, challenges still remain in ensuring equitable and sustainable coverage. The SSA region has struggled to achieve and maintain high levels of immunization coverage due to various factors, including weak health systems, vaccine hesitancy, limited resources, political instability and other as yet undetermined reasons ^{7, 8}. These challenges can be better understood by conspiring the experience of under-vaccinated and zero-dose children.

While the number of under-vaccinated children (those who have not received all three doses of the Diphtheria Tetanus and Pertussis (DTP3) vaccine) has decreased globally from about 22 to 20 million between 2010 and 2019 respectively, the geographical distribution of where these children reside has equally evolved, as shown in Figure 1 below ^{9, 10}. The percentage of children under-vaccinated for DTP3 globally has increased from 25% to 32% in West and Central Africa, while in almost every other region it has either remained stagnant or decreased; for instance, in South Asia it dropped from 38% to 20% ^{10, 11, 12}. Similarly, the number of children with zero-doses (those who have not received the first DTP dose) has barely decreased from 15 to around 14 million between 2010 and 2019. However, nearly two-third of the countries contributing to the zero-dose figure are concentrated in ten countries, four of which in SSA (Angola, Ethiopia, the DRC Congo and Nigeria), yet these countries carry the highest burden ^{7, 13, 14, 15}. It is pertinent to ask why the SSA region has not improved significantly in terms of immunization coverage, despite an increase in public expenditure on immunization in the region. Although expenditure on vaccination does not necessarily predict coverage of basic vaccines compared to expenditure on health ¹⁶. However, as assessment of immunization financing provides further arguments for increasing the state’s budgetary provision, with all other variables remaining constant.

Figure 1.Global share of under-vaccinated children for DTP3 (2010 – 2019). (10,13)

Data shows that, globally, the cost of immunizing each surviving infant is US$68, equivalent to US$1.30 per capita, and represents 0.02% and 0.3% of the global Gross Domestic Product (GDP) and current health expenditure, respectively ^{17, 18}. The weight of the financial burden of immunization varies between the low- and middle-income countries (LMICs) and the Western, Educated, Industrialized, Rich and Democratic (WEIRD) or High-Income Countries (HICs) ^{19, 20, 21}. The WEIRD countries spend more on immunization per capita and their government fund a larger proportion of the total immunization expenditure ^{19, 22}. Therefore, it is assumed that the disparity in coverage between HICs/WEIRD countries and LMICs is a result of state spending on immunization.

However, the relationship between immunization spending and immunization coverage has not been found to be directly linked. Nevertheless, it is worth exploring further, given that even countries in the same World Bank economic grouping have different immunization outcomes or coverages. For example, both Burkina Faso and Guinea (Gavi low-income countries) spend about US$35 on immunization per surviving infant ^{21, 22, 23}. However, while Burkina Faso has maintained a rate of unvaccinated and under-vaccinated children below 10%, even after introducing additional vaccines such as the second measles dose, the pneumococcal conjugate vaccine, the rubella vaccine and the rotavirus vaccine, Guinea’s the rate of unvaccinated and under-vaccinated children exceeds 50% ^{17, 20, 21}. This scenario is not limited to low-income countries. It can also be seen in middle- and high-income countries.

Although studies on factors influencing vaccination coverage in SSA are abundant, few examine the extent to which immunization performance is related to the state’s public expenditure on immunization. Therefore, this study aims to analyze the factors affecting the performance of the immunization program in 37 Gavi-eligible countries in SSA, with a particular focus on the relationship between public expenditure on immunization and immunization coverage.

A direct relationship between immunization financing and immunization coverage would be a critical game changer, given that countries are transitioning out of Gavi funding for immunization and there has been long-standing advocacy for increased budgetary allocation by SSA countries. Some countries achieve much higher coverage with the same investment, while others invest considerably more but do not immunize a greater percentage of their population. A correlation or lack of it between these two dynamics and other secondary variables would strengthen the evidence based for policy action. By identifying the factors that influence the performance of the immunization program in Gavi-eligible SSA countries, this study will enhance the evidence based for policies and strategies that can improve immunization coverage and ultimately contribute to reducing VPD and deaths in SSA.

The descriptive statistics (Table 1) and the correlation matrix (Table 2) provided interesting insights into the relationship between the study variables. They provided significant explanations that enabled the study outcomes to be determined. The outcome and code variables included GNI per capita (InGNIpercapAtlas), GNI per capita squared (InGNIquare), corruption perception index (CPI), membership of the English-speaking zone (I.AA), and government expenditure on immunization per child (Gov_expRIchd). Basic vaccination coverage among the 37 assessed countries increased by 6% over about two decades (2006-2019), as did GNI per capita and government expenditure on immunization per child, which increased significantly by around 200% between 2006 and 2019. Similarly, the countries’ official government corruption perception score improved significantly during this period, rising from 25% to 30%.

Table 1. Descriptive statistics for model variables

Variable	2006	2019	Mean	Std. Dev.	Min	Max
DTP3Coverage	72.1842	78.421	76.387	17.672	19	99
lnGNIpercapAtlas	6.290	6.905	6.729	.631	5.011	8.519
lnGNIquare	39.916	48.042	45.682	8.563	25.106	72.577
Gov_expRIchd	1.789	4.326	3.091	3.038	0	26.129
CPI	24.818	30.132	27.804	8.607	1.5	56
GNIpercapAtlas	606.316	1160.526

This study produced a wealth of new insights relating to the primary objective of understanding the factors influencing the performance of immunization programs and their relationship with public expenditure in the 37 Gavi-eligible countries in SSA. The average GNI of Gavi-eligible SSA countries increased from US$639 to US$1,192 per capita, while government spending on immunization, excluding external financing, increased from US$1.7 to US$4.5 per child. The results of the study also confirm a strong correlation between reduced corruption, improved immunization financing, increased GNI and improved immunization coverage in Gavi-eligible SSA countries. However, performance declines beyond a threshold increase in the GNI. This poses a challenge to maintaining achievements in Gavi transition countries.

The study demonstrates that there is a positive correlation between immunization coverage and financing, though this is not necessarily the case for health sector financing in general. Remarkably, for 1% increase in GNI, there was a staggering 10.49% increase in immunization coverage. The study outcomes also align with existing evidence that, where GNI increases, the priority in the allocation of health sector funding tends to shift from primary healthcare to hospital spending ^{32, 33, 34, 35, 36, 37}. This is because a fall in immunization coverage is confirmed above a certain wealth threshold as the country’s GNI increases. However, it was unable to prove that, despite an upward trend in GNI, countries were able to spend US$60 per child per year to cover immunization needs. This situation could be exacerbated by the economic contraction following the COVID pandemic, which reduces the availability of funds in developing countries for finance health expenditure in general, and for immunization expenditure in particular. This is particularly pertinent given that the pandemic itself has put significant stain on health systems.

The effect demonstrated by Anglophone (English-speaking) SSA countries, which experienced a clear improvement in immunization coverage compared to the Francophone (French-speaking) SSA countries, requires the attention of country-level policymakers and global/regional health governance. Lessons learnt from the English-speaking countries could have a contagious effect, if positive elements are transposed to improve immunization coverage in French-speaking countries.

In Francophone Africa, the introduction of Human Papillomavirus (HPV) vaccine, which prevents cervical cancer, is progressing very slowly, with coverage lagging significantly behind that of Anglophone countries ^{38, 39, 40}. Of the 15 countries in the Economic Community of West African States (ECOWAS), 11 are French-speaking, yet only four of these, namely Burkina Faso, Côte d'Ivoire, Cameroon, and Senegal have introduced the HPV vaccine into their National Immunization Programs (NIPs) ^{41, 42, 43}. This situation underscores a considerable disparity within the region, and given the analysis of public expenditure for immunization, these outcomes are not surprising. As observed for specific vaccines such as HPV, this situation is widespread for all vaccines. Hence, there is a need to strengthen communication, awareness, community engagement and cultural acceptance, as well as political commitment and, most importantly, improved financial resource allocation.

It is commendable that the GNI per capita has steadily increased in the countries eligible for Gavi funding in SSA, reaching twice its initial value during the study period. Similarly, such growth could also be observed in the evolution of immunization expenditure per child, which rose from US$1.7 to US$4.5 between 2006-2019. This significant growth demonstrates a substantial increase in willingness and behavioral change with regards to financing immunization, to the extent that the amount has been more than doubled per child within the last two decades. However, as Figure 3 shows, there is likely a threshold beyond which coverage tends to fall despite the increase in GNI. Although, the parametric regression on panel data confirmed a trend of the threshold relationship, however, the coefficient has no significant value. As GNI is crucial in determining eligibility for Gavi funding, the negative influence of its evolution on immunization coverage deserves particular attention to ensure the sustainability of gains during the support period. Therefore, significant observation and action are needed to understand the decline in immunization coverage syndrome after certain GNI thresholds.

When assessed predictors are used to determine the primary determinant or dependent variable, the measure of immunization coverage shows that coverage drops within the period under study in relation to GNI per capita and its square. However, the opposite was observed in relation to whether or not the country is perceived to be corrupt and expenditure on immunization per child. This means that, on average, whenever GNI increases, immunization coverage decreases and vice versa. However, government spending on immunization per capita and the perception of corruption in countries have a positive effect on vaccination uptake. This is an important talking point for advocacy among state actors to increase fiscal responsibility towards immunization. Furthermore, the disparity between GNI per capita and immunization coverage seems to be an anomaly that requires much closer exploratory research. However, improved GNI per capita alone does not guarantee better immunization coverage when other barriers such as vaccine hesitancy, literacy and communication issues, misinformation, trust in vaccines and the healthcare systems, masculinity and gender disparity bias, cultural and religious practices, wealth disparity within countries, inadequate or poorly trained healthcare personnel, and so on remain constant, particularly in SSA ^{44, 45, 46, 47, 48, 49, 50}. I.e., improved population’s economic wellbeing alone does not mitigate the socio-economic, psychological, socio-cultural and behavioral constraints that affect immunization coverage. However, a better understanding of this association in the SSA context would help state and non-state actors to develop more effective intervention strategies and adaptable plans for programs that promote immunization coverage.

In other low income and middle income (LMICs), e.g., the English- and Dutch-speaking Caribbean subregions of the Americas, where political will and government expenditure on immunization have been particularly strong, alongside factors such as dedicated healthcare workers (HCWs) and quality surveillance, resulting in the eradication of wild polio for 34 years, measles for 25 years, CRS for 17 years, and rubella for 15 years, immunization coverage has been remarkably positive ^{51, 52}. Strong political will tends to manifest in financial, policy, and legislative support, and this combination is essential for systems fulfil their mandates.

Another notable finding of the study is the reaction of immunization coverage vis-à-vis public expenditure on immunization and health system in general. In contrast to the countries’ immunization financing, the percentage of expenditure on health shows a negative trend compared to the former. That is, although this was not the primary outcome of the study, the relationship between vaccination coverage and health expenditure shows stagnation or even retrogression, particularly in Gavi-eligible French-speaking SSA countries. It was clear that English-speaking Gavi-eligible SSA countries allocated a higher percentage of government expenditures to immunization needs consequently achieved positive immunization outcomes. Similarly, French-speaking Gavi-eligible SSA countries allocate a lower proportion of their public spending to immunization costs, resulting in the corresponding negative immunization coverage reported.

The study had some classic limitations relating to the completeness of the data on Gavi-eligible SSA countries, especially the omission of Somalia and South Sudan. Beyond the figures themselves, there are other yet to be considered but essential parameters linked to the cost of vaccines and the methods of purchase, which are not the same in all countries and could therefore have an influence on expenditure on immunization. The quality and availability of existing data is another factor to consider, particularly the reliance on Comprehensive Multi-Year Plan (cMYP) data. While cMYP data are currently the best source of information on the costing and financing of immunizations in LMICs, they are compiled for Gavi applications and may contain inconsistencies in cost definitions and calculations and potentials for weak validation methods.

This study shows that, despite an increase in the GNI per capita of Gavi-eligible countries in SSA, more needs to be done to improve the financing of immunization at a country-level. Furthermore, it demonstrates that an increase in GNI does not necessarily translate into an improvement in immunization coverage. There is a risk of immunization levels depreciating with an immediate effect on program performance, at a time when Gavi is disengaging from these countries. Therefore, there is a significant risk of losing the programs’ achievements after Gavi’s support ends and countries become ineligible. Integrating immunization into essential health services is important for enhancing the sustainability of immunization coverage. Improving equitable access to vaccines, addressing socio-cultural challenges and strengthening healthcare infrastructure could enhance the performance of immunization programs and their relationship to public expenditure in SSA countries.

Another critical takeaway is the Anglophone effect, which requires further exploration to better adapt advocacy in Francophone countries and ensure sustainable improvements in the immunization coverage. Further research is also advised to understand the factors preventing an increase in immunization coverage beyond a certain GNI threshold.

CAREC - Caribbean Epidemiology Centre

EPI - Expanded Program on Immunization

HPV - Human Papillomavirus

SSA - Sub-Saharan Africa

UNICEF - United Nations International Children’s Emergency Fund

WHO - World Health Organization

MOH - Ministry of Health

RI - Routine Immunization

LMIC - Low- and Middle-Income Countries

AUCDC - Africa Union Centre for Disease Control

cMVP - Comprehensive Multi-Year Plan

VPD - Vaccine Preventable Diseases

AMP - Agence de Medicine Preventive

Gavi - Gavi the Vaccine Alliance

DTP3 - Three doses of Diphtheria Tetanus and Pertussis

Zero-dose - Incomplete dose of Diphtheria Tetanus and Pertussis

Under-vaccinated - Children who have not received the first dose of DTP

WEIRD - Western Educated Industrialized Rich and Democratic (WEIRD)

HIC - High-Income Countries

GNI - Gross National Income

CPI - Corruption Perception Index

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