Abstract
Africa bears the greatest brunt of under-five mortality in the world. Among the major approaches used in tackling under-five deaths is childhood immunisation. While income is regarded as a major determinant of demand for child health inputs including immunisation, the existing studies are microlevel analyses, which do not provide a bigger picture of how an enhancement in economic growth (aggregate income) contributes to the utilisation of childhood immunisation in an economy as a whole. Since Africa has experienced economic growth in the recent decades, this study aims to fill this gap in the literature by examining the contribution of economic growth to the utilisation of childhood immunisation in selected African countries. The study uses a panel design involving data on 50 African countries over the period, 2002 to 2019. Utilisation of DPT (diphtheria, pertussis (or whooping cough) and tetanus) and measles immunisation are used as proxies for childhood immunisation while the system Generalised Method of Moments (GMM) regression is used as the estimation technique. We find economic growth to have a positive significant effect on the utilisation of childhood immunisation. Thus, it is imperative to intensify the enablers of economic growth in Africa in order to increase the utilisation of childhood immunisation.
Introduction
Under-five mortality remains a major public health problem, especially in Africa. In 2020, out of the 5 million deaths reported among children under-5 years, more than 80% of these deaths happened in Sub-Saharan Africa (SSA) and southern Asia. 1 Moreover, in the same year, SSA had the highest rate of under-five mortality-74 deaths per 1000 live births-, which was twice the global rate and 14 times greater than the risk for children in North America and Europe. 1
A major approach recognised in dealing with under-five mortality is immunisation. For instance, between 2000 and 2022, 57 million deaths were averted as a result of measles vaccination. 2 In addition, deaths of newborns attributed to tetanus reduced by 97% between 1988 and 2018 largely as a result of scaling-up immunisation. 3
Nonetheless, the coverage of childhood immunisation falls below the recommended targets. For instance, in 2022, infants numbering 14.3 million did not receive the first (initial) dose of the DPT (diphtheria, pertussis (or whooping cough) and tetanus) vaccine while 6.2 million infants had received partial vaccination. 4 Among these 20.5 million infants, a little below 60% of them lived in 10 countries of which 5 were on the African continent (Angola, the Democratic Republic of the Congo, Nigeria, Ethiopia and Mozambique). 4
To enhance the coverage of childhood immunisation, it is important to know the factors that determine its utilisation or uptake. This has led to a number of empirical studies that have examined the factors associated with the utilisation of childhood immunisation or vaccination in African countries.5 -12 Nonetheless, to the best of our knowledge, these past studies focussed on the microlevel (household or individual level data) hence they have not provided an understanding of the determinants of the utilisation of childhood immunisation at the macrolevel (aggregate or overall level). Meanwhile, doing a macrolevel analysis provides a wider insight into the determinants of childhood immunisation uptake. Per the theory of demand for health inputs, 13 a major potential macrolevel determinant of childhood immunisation uptake is economic growth, since it is a general indicator of the level of income in an economy as a whole. Therefore, since Africa has experienced some improvements in economic growth in recent times or decades (For instance, 1.27%, 2.44% and 2.65% economic growth rates in 2016-2018 respectively, in SSA), 14 this study aims to investigate the effect of economic growth on the utilisation of childhood immunisation in Africa, while controlling for other factors.
By conducting this study, we provide the first empirical evidence of how economic growth has affected the uptake of childhood immunisation in Africa. We find that an increase in economic growth is associated with a rise in the utilisation of childhood immunisation even after robustness checks. The findings therefore shed light on the role economic growth can play in enhancing the utilisation of childhood immunisation, which is very critical towards child survival. Moreover, an improvement in child survival will aid in attaining the Sustainable Development Goal (SDG) 3.2 (ie, stop avoidable deaths of under-five children and newborns, with all countries targeting a reduction in neonatal mortality and under-five mortality to 12 and 25 per 1000 live births respectively, by 2030). 15
Methods
Study design
This study uses a panel design involving 50 African countries (see Table 3) with annual data spanning the period, 2002 to 2019. The number of countries used is based on data availability and the period is selected to reflect the observance of economic growth in Africa in recent times or decades. Moreover, we do not go beyond 2019 because the COVID-19 pandemic caused disruptions in economic growth and the utilisation of childhood immunisation across countries after 2019. The panel design is used because the study involves several countries with data over a number of years. Using such design aids in tackling omitted variables bias as well as enhancing the precision of inferences emanating from parameter estimates. 16
Data and variables
The study sources data from the World Development Indicators (WDI) of the World Bank. 17 The utilisation of childhood immunisation (CIM), measured by DPT and measles immunisation uptake are used as the dependent variables. The main independent variable is economic growth (EG). Three measures of economic growth are used: 1 measure is used in the baseline analysis (economic growth1) and 2 measures are used for robustness checks (economic growth2 and economic growth3). Based on literature,13,18 -24 health expenditure (E), primary educational enrolment (education (PE)), under-five mortality (UM) and population growth (PG) are used as control variables. Details of how the variables are measured as well as their expected signs can be found in Table 1.
Measurement and expected signs of variables.
‘+’ Means will increase immunisation uptake.
As regards the expected signs of the variables, based on the theory of demand for health, 13 we expect increments in economic growth, health expenditure and education to be associated with a rise in the utilisation of immunisation. Thus, economic growth implies an improvement in income which would enhance the ability of people to pay for costs associated with immunisation uptake. Also, education is expected to have a positive association with the utilisation of immunisation given that people with formal education are more likely to be informed about the importance of immunisation relative to those without formal education. 9 Similarly, current health expenditure is expected to have a positive association with the utilisation of childhood immunisation because, an increase in health expenditure implies more spending on the supply and demand for health consumables such as vaccines. For under-five mortality, as it increases, perceived susceptibility to childhood mortality will be high. This, according to the health belief model, 18 will increase the willingness of caregivers to utilise immunisation for their children in order to protect their lives, assuming that the perceived barriers are less than the perceived benefits. We therefore expect a positive association between under-five mortality and the utilisation of childhood immunisation. As population growth increases, it is expected that more efforts will be made to increase the availability of vaccines for children, and there would also be higher demand for vaccines. We therefore expect the effect of population growth on the utilisation of childhood immunisation to be positive.
Statistical analysis
The association between the utilisation of childhood immunisation and economic growth is examined by specifying the functional relationship below:
where all notations are as already defined. Equation (1) is re-specified in a more estimable form as follows:
where i, t,
For the estimation technique, we use the dynamic panel system Generalised Method of Moments (GMM) regression of Arellano and Bover 25 and Blundell and Bond 26 to estimate equation (2). The system GMM is chosen for the following reasons: (i) it is able to capture the persistence of dependent variables overtime, (ii) it is able to deal with the problem of endogeneity emanating from the persistence term correlating with the error term and (iii) it is capable of handling problems associated with the dependent variable being able to affect the independent variables, which is also a form of endogeneity.20,21,27 -32
The system GMM employs past values of independent variables as instruments as well as level and first difference equations in dealing with endogeneity. The suitability of the system GMM estimates is determined by the absence of overidentification and second-order serial correlation as well as avoiding the proliferation of instruments. Hence, the insignificance of the P-values of the Hansen overidentification test (Hansen j) and the Arellano-Bond second-order serial correlation test (ARB) are used to establish the absence of overidentification and second-order serial correlation, respectively. To avoid the proliferation of instruments, the number of instruments should be less than the number of countries.20,21,27 -32
To prevent the challenge (aberration) associated with high recurrent data and avoid the proliferation of instruments as well as make our data more suitable for the system GMM estimation,27,33 we take 3 years averages of our data. The averaged data are used for all the analyses except the graphs. Given the huge figures of the baseline economic growth measure (economic growth1), in running the system GMM, we log-transformed it in order to reduce its differences with other variables in terms of measurement. 34 However, before the system GMM results, univariate analysis of the variables are presented.
Results
The study results are presented in this section under 2 sub-sections namely, univariate analysis and multivariate analysis.
Univariate analysis
Descriptive statistics of the study variables and country-level analysis of childhood immunisation are presented in this sub-section.
In Table 2, it can be seen that on the average, 79.059% and 76.604% of children in the selected countries have received DPT and measles immunisation, respectively. The average GDP (economic growth1) over the study period is $39.480 billion, while the average growth rates of per capita GDP (economic growth2) and GDP (economic growth3) are 1.862% and 4.33% respectively. The average health expenditure as a percentage of GDP is 5.235%. Also, on the average, primary education enrolment is 99.395%, under-five mortality per 1000 live births is 83.083 and population growth rate is 2.403%.
Descriptive statistics of variables.
Variables are not log-transformed.
Over the study period, the highest and least utilisation of both DPT and measles immunisation can be found in Seychelles and Chad, respectively (Table 3).
Childhood immunisation utilisation per country, 2002 to 2019.
In Figure 1, over the study period (2019 figure less 2002 figure), it can be seen that Botswana, Central African Republic, Egypt, Guinea and Mauritania experienced a decrease in the utilisation of DPT immunisation among children, with Mauritania having the greatest decrease. The utilisation of DPT immunisation for children in Tanzania and Seychelles did not change while all the remaining countries show an increase in the utilisation of DPT immunisation for children, with the greatest increase (42%) found in Niger and Sierra Leone.

Change in DPT immunisation per country, 2002 to 2019.
Algeria, Angola, Central African Republic, Egypt, Eswatini, Gambia, Madagascar, Mauritania and Tanzania exhibit a fall in the utilisation of measles immunisation for children and the highest decrease can be found in Eswatini and Mauritania. All the remaining countries exhibit an increase in the utilisation of measles immunisation among children and the biggest increment is found in Niger (38%) (Figure 2).

Change in measles immunisation per country, 2002 to 2019.
Multivariate analysis
The baseline (Table 4) and robustness checks (Table 5) system GMM estimates of the effect of economic growth on the utilisation of childhood immunisation are presented in this sub-section.
Baseline 2-step system GMM estimates of the effect of economic growth on the utilisation of childhood immunisation.
Abbreviations: ARB, Arellano-Bond second-order serial correlation test statistic; Hansen j, Hansen overidentification test statistic; L., first lag of the associated variable.
Economic growth1 is log-transformed; For brevity, time fixed effects are not reported; Standard errors in parentheses; *P < .1, **P < .05, ***P < .01.
Robustness checks 2-step system GMM estimates of the effect of economic growth on the utilisation of childhood immunisation.
Abbreviations: ARB, Arellano-Bond second-order serial correlation test statistic; Hansen j, Hansen overidentification test statistic; L., first lag of the associated variable.
For brevity, time fixed effects are not reported; Standard errors in parentheses; *P < .1, **P < .05, ***P < .01.
In the baseline results, the lags of childhood immunisation utilisation or uptake have positive significant effects on the current levels of immunisation uptake, which indicates the persistence of childhood immunisation overtime (Table 4).
Regarding the main variable of interest, we find a positive significant association between economic growth and the utilisation of childhood immunisation (Table 4). Since in the baseline economic growth is log-transformed and the utilisation of childhood immunisation is not log-transformed, we have to divide the coefficients of economic growth by 100 to ensure a better interpretation. 35 Thus, given the coefficients of 1.298 and 1.629 for economic growth in the DPT and measles models respectively, the interpretation is that, a percentage increase in economic growth is associated with an increase in the utilisation of DPT and measles immunisation for children by 0.013% and 0.016% respectively, at the 1% level of significance (Table 4).
Further, in Table 4, health expenditure is found to have a positive significant effect on the utilisation of both DPT (β = .770, P < .01) and measles (β = .933, P < .01) immunisation. In addition, the findings show an increase in educational enrolment to be associated with an increase in the utilisation of measles immunisation (β = .050, P < .05). Nonetheless, we find an increase in under-five mortality to be associated with a decrease in the utilisation of both DPT (β = −.114, P < .01) and measles (β = −.100, P < .05) immunisation. Further, when population growth increases, it is found to be associated with an increase in the utilisation of DPT immunisation (β = 2.341, P < .01).
In the robustness checks results, the lags of the dependent variables maintain their positive significant coefficients, hence confirming the persistence of immunisation utilisation overtime. Regarding models using the second measure of economic growth (Economic growth2), we find a positive significant association between the second measure of economic growth, and the utilisation of DPT (β = .615, P < .01) and measles (β = .451, P < .01) immunisation. Similarly, health expenditure and educational enrolment are found to have positive significant association with the utilisation of immunisation (DPT: β = .464, P < .05; measles: β = .346, P < .1 (for health expenditure), DPT: β = .114, P < .01; measles: β = .141, P < .01 (for educational enrolment)). In addition, a rise in under-five mortality is found to be associated with a fall in the utilisation of DPT (β = −.143, P < .01) and measles (β = −.071, P < .05) immunisation. However, population growth is found to have a positive significant association with the utilisation of immunisation (DPT: β = 3.611, P < .01; measles: β = 1.144, P < .01) (Table 5).
Using the third measure of economic growth (Economic growth3), we find a positive significant association between economic growth and the utilisation of immunisation (DPT: β = .527, P < .01; measles: β = .436, P < .01). The signs and significance of the control variables are similar to the other models even when the third measure of economic growth is used (Table 5).
Discussion
To the best of our knowledge, this study provides the first empirical evidence of the effect of economic growth on childhood immunisation utilisation across African countries. As expected, economic growth is found to have a positive significant association with the utilisation of childhood immunisation. The implication is that, the economic growth experienced on the African continent has been beneficial to the utilisation of childhood immunisation. Moreover, although for some few countries childhood immunisation rates in 2019 were less than that of 2002 (Figures 1 and 2), so far as the immunisation rates for all the years are positive (Table 2), economic growth can be said to be a major contributory factor. This finding is in line with the theory of demand for health which postulates a positive association between income and the demand for health inputs. 13 Thus, rising economic growth is likely to be associated with an enhancement in the ability of governments to afford and supply health inputs (such as vaccines) to their citizens. Moreover, rising economic growth could be associated with an enhancement in income at the household level which could increase the ability of households to afford child health inputs. For instance, childhood vaccination (hence, immunisation) may be free but transportation cost may be incurred to reach vaccination sites, hence, people without money will not be able to afford and access vaccination. Our finding concurs with past microlevel studies on the role of household income or wealth in the utilisation of child health inputs.5,6
Since people exposed to formal education are more likely to know about the importance of immunisation in preventing diseases and deaths, 9 it is not surprising that our findings reveal a positive association between educational enrolment and the utilisation of childhood immunisation. The finding on the role of education in utilising childhood immunisation is supported by several microlevel studies on the African continent.6,8 -10,36,37 Therefore if education has positive association with the uptake of health inputs such as immunisation, it is not surprising that a number of studies21,38,39 have found education to be associated with an enhancement in health outcomes.
Given that rising spending on health could increase the supply of vaccines and also connotes that people could afford cost in accessing vaccination such as transportation cost, it is not surprising that we find a positive significant association between health expenditure and the utilisation of childhood immunisation.
Surprisingly, a rise in under-five mortality is found to be associated with a fall in the utilisation of childhood immunisation. This finding conflicts with the health-belief model, 18 which posits that, when people feel more susceptible to contract diseases or die, they will be more willing to utilise health inputs, assuming that the perceived barriers are less than the perceived benefits. Nonetheless, the possible explanation is that, if under-five mortality is increasing and people are not aware that the non-utilisation of immunisation could be one of the possible reasons, the utilisation of immunisation will not increase. Moreover, deep-seated negative perceptions about vaccines may prevent people from utilising immunisation for their children even if under-five mortality is high.
The finding of a positive significant association between population growth and the utilisation of childhood immunisation is not farfetched because, when population increases, governments are likely to ensure a commensurate rise in investment in the health sector which could increase the supply of health inputs 19 such as vaccines. Moreover, the rise in population growth implies the number of children in need of vaccines would increase, hence, increasing the utilisation of childhood immunisation, all other things being equal.
Limitations
Notwithstanding the novelty of our study, it is not without limitations. First, due to data paucity, four African countries were not added to our study, hence could limit the generalisation of our findings to the entire continent, although we contend that using 50 out of 54 countries is representative of the African continent. Second, we do not cover the utilisation of other childhood immunisation against diseases such as polio, yellow fever among others. Studies in the future may therefore focus on addressing these limitations.
Conclusion
The study findings highlight the potential role economic growth can play in the utilisation of childhood immunisation which is critical in lessening the burden of under-five mortality on the African continent. Therefore, measures such as skills development, technological advancement among others that can propel economic growth 24 on the African continent should be deepened in order to increase the uptake of child health inputs such as vaccines. Moreover, enhancing educational enrolment and health expenditure on the African continent will also be very critical towards decreasing under-five deaths since they are associated with an enhancement in childhood immunisation uptake.
Footnotes
Acknowledgements
Not applicable.
Funding:
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Declaration of conflicting interests:
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Author Contributions
Conceptualisation: MI; Data acquisition: MI; Analysis: MI; Interpretation: MI; Writing of original draft: MI, AA; Critical revision for important intellectual content: MI, AA; All authors read and approved the final version of the manuscript.
Ethics Approval and Consent to Participate
Consent to participate or ethical approval is not needed since aggregated data from secondary sources are used for this study.
Consent for Publication
Not applicable.
