Abstract

Background

Bacillus Calmette-Gu茅rin (BCG) vaccination is a cornerstone of childhood immunisation programs, protecting against tuberculosis (TB), a major public health concern. Sierra Leone, a West African nation, faces challenges in achieving equitable and high BCG immunisation coverage. This study delves into the trends and inequalities in BCG coverage among one-year-old children in Sierra Leone between 2008 and 2019.

Methods

Three rounds of data from the Sierra Leone Demographic and Health Surveys (2008, 2013, and 2019) were used to analysed to examine the inequalities in BCG coverage. Simple measures of inequality [Difference (D) and Ratio (R)] and complex measures of inequality [Population Attributable Ratio (PAR) and Fraction (PAF)] were calculated in the World Health Organization鈥檚 Health Equity Assessment Toolkit (WHO鈥檚 HEAT) software. The measures were calculated separately for each of the three surveys for age groups of women, level of education, economic status, residential areas, gender, and sub-national provinces, and their estimates were compared.

Results

The findings revealed that BCG immunisation coverage in Sierra Leone has increased significantly from 2008 (82.0%) to 2019 (96.3%).听Age-related inequalities between children of older mothers (20-49) and younger mothers (15-19) increased from a听Difference of -4.7 percentage points in 2008 to 4.8 percentage points in 2019. The PAF increased from zero in 2008 to 0.4% in听2019. This means that in the absence of age-related inequalities, the national average of BCG immunisation coverage would have increased by 0.4%. Economic-related inequalities between children of mothers in Quintile 5 (richest) and Quintile 1 (poorest)听decreased from a Difference of 9.2 percentage points in 2008 to 1.2 percentage points in 2019. Educational-related inequalities听between children of mothers with secondary/higher education and no education decreased from a Difference of 14.1 percentage听points in 2008 to 0.4 percentage points in 2019. The PAF decreased from 13.3% in 2008 to 0.2% in 2019, indicating that without educational-related inequalities the setting average of BCG immunisation coverage would have increased by 0.2%. Place听of residence-related inequalities between children of mothers living in urban areas and rural areas decreased from a Difference听of 9.3 percentage points in 2008 to 0.7 percentage points in 2019. The PAF decreased from 8.5% in 2008 to 0.5% in 2019听indicating that the national average of BCG immunisation coverage would have increased by 0.5% without place of residence-related听inequalities. The sex of the child-related inequalities between male and female children decreased from a Difference of听5.4 percentage points in 2008 to 0.7 percentage points in 2019. The PAF decreased from 3.3% in 2008 to 0.4% in 2019听indicating that the national average of BCG immunisation coverage would have increased by 0.4% without sex of the child-related听inequalities. Provincial inequalities decreased from a Difference of 18.5 percentage points in 2008 to 2.3 percentage听points in 2019. The PAF decreased from 14.3% in 2008 to 1.1% in 2019 indicating that the national average of BCG听immunisation coverage would have increased by 1.1% without provincial inequalities.

Conclusion

The findings indicate a substantial improvement in BCG immunisation coverage in Sierra Leone among one-year-olds,听reflecting successful public health initiatives. However, age-related inequalities have worsened, with coverage among children听of younger mothers declining relative to those of older mothers, suggesting a need for targeted interventions for this population.听In contrast, economic, educational, sex, and place of residence-related inequalities have notably decreased, indicating progress听in equitable access to immunisation across different socioeconomic strata. Additionally, provincial inequalities have decreased听significantly, yet a difference of 2.3 percentage points remains, highlighting the need for continued efforts to ensure that all听provinces, receive adequate healthcare resources and outreach. The absence of economic-related inequality by 2019 is听particularly encouraging, as it suggests that economic barriers to immunisation have been effectively addressed. Furthermore,听the reduction in educational and provincial inequalities highlights the effectiveness of strategies aimed at improving access and听awareness in underserved areas.

Introduction

The BCG vaccination is crucial in the worldwide fight against tuberculosis [1]. Vaccination is essential for safeguarding children against the morbidity and mortality associated with vaccine-preventable illnesses (VPDs). The BCG vaccination comprises a weakened form of Mycobacterium bovis that can prevent severe manifestations of tuberculosis, such as meningitis and disseminated tuberculosis [2, 3]. BCG vaccine is administered to all newborn infants in countries with a high prevalence of tuberculosis, such as India, Ethiopia, and Sierra Leone. In nations with a low incidence of tuberculosis, efforts are focused on specific groups of people who are at a higher risk of contracting tuberculosis [4, 5].

Despite numerous attempts to enhance the availability and extent of BCG vaccination, tuberculosis continues to be a significant health issue for children in impoverished nations such as Sierra Leone [6, 7]. The World Health Assembly approved the Global Vaccine Action Plan 2011鈥�2020 to serve as a strategy for optimizing the benefits of vaccination and achieving the goal of universal access to vaccines and immunisation with a coverage rate of 90% [8]. With support from international organisations, Sierra Leone has implemented various measures to enhance the national coverage of BCG vaccination as part of its worldwide agenda. Over the past few decades, the coverage of BCG vaccination has been improved in Sierra Leone through the joint efforts of reaching every district approach, a health extension programme, and the implementation of enhanced routine immunisation Activities [9]. Immunisation coverage has increased due to significant efforts to restore the country鈥檚 health system after a ten-year civil war and the Ebola virus disease outbreak in 2014 and 2015 [10]. According to the World Health Organisation (WHO), 73% of children in Sierra Leone received the BCG vaccine in 2022 [11].

Several factors, including the mother鈥檚 sociodemographic and economic condition, can affect BCG immunisation coverage [12,13,14,15]. Prior research conducted in industrialized nations indicated that the prevalence of BCG vaccination was linked to family-related factors such as wealth index, literacy rate, and healthcare access [16, 17]. Another crucial determinant that substantially influences vaccine utilization in Africa is the cost-effectiveness and management of immunisation records [18]. Misconceptions regarding vaccines are an additional determinant impacting vaccine coverage [19].

The WHO has devised numerous strategies and tools to strengthen the ability to track disparities in health as a fundamental aspect of its committed endeavours to attain fairness in health [20, 21]. A noteworthy software called the Health Equity Assessment Toolkit (HEAT) is free and open source. It helps assess and monitor inequalities in a country for several health indicators, such as BCG vaccine coverage. It specifically targets low- and middle-income countries [21]. This software enables computation of both basic and complex inequality metrics. Additionally, various materials and updates are accessible to the public [20, 22]. This study employs the HEAT to examine selected measures of both simple and complex inequalities. The objective is to thoroughly comprehend the trends in BCG vaccination coverage over time and its inherent disparities.

As Sierra Leone continues to rebuild and strengthen its healthcare system, particularly in the aftermath of the Ebola outbreak and amidst ongoing global health challenges, this study analyses the trends and inequalities in BCG vaccination coverage for one-year-olds in Sierra Leone from 2008 to 2019. By understanding these trends and inequalities, we can gain valuable insights into the effectiveness of Sierra Leone鈥檚 immunisation program. This knowledge is essential for policymakers and healthcare professionals to design targeted interventions that ensure equitable access to BCG vaccination for all one-year-olds, ultimately improving child health and well-being in Sierra Leone.

Methods

Study setting and data source

We used data from 2008, 2013, and 2019 SLDHS. The survey datasets are available for free on the website . The SLDHS is a nationwide survey that aims to identify consistent trends and changes in demographic indicators, health indicators, and social issues among individuals of all genders and age groups. The SLDHS had a cross-sectional design in which participants were chosen using a stratified multi-stage cluster sampling method. A detailed description of the SLDHS sampling methodology and technique can be found in the report [23]. This study comprised women who had given birth within two years before the survey. The analysis used 1,060 data points from the 2008 SLDHS dataset, 2,168 data points from the 2013 SLDHS dataset, and 1,837 data points from the 2019 SLDHS dataset. The 2008, 2013, and 2019 SLDHS data were available through the WHO HEAT online platform [21]. This study was done considering the guidelines in the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) [24].

Variables

The outcome variable was the coverage of BCG immunisation. The women in the SLDHS were surveyed regarding the extent of BCG immunisation they received at a healthcare facility during their most recent pregnancy. Women whose children were administered BCG immunisation were assigned the category 鈥�1鈥�, whereas those whose children did not receive it were classified as 鈥�0鈥�. The study utilized six variables as inequality stratifiers identified in existing literature [15, 25,26,27]. These variables include the age of the women, level of education, economic status (wealth quintile), type of place of residence, sex, and sub-national area. The WHO HEAT software included these stratifiers for evaluating disparities in several health and social indicators [21]. The stratifiers encompass various categories such as age groups for women (15鈥�19 and 20鈥�49), educational attainment levels (no education, primary, and secondary and above), economic status (poorest, poorer, middle, richer, and richest), residential areas (rural and urban), gender (female and male), and sub-national provinces (Eastern, Northern, Northwestern, Southern, and Western).

Statistical analysis

All analyses were conducted using the WHO HEAT online software [21]. The WHO HEAT is an internet-based statistical tool used to examine health inequalities within and among nations, utilizing a range of health and social indices [21]. The literature [20, 22] comprehensively explains the statistics package WHO HEAT. We analysed the prevalence of BCG immunisation coverage across six factors that indicate disparity: age, place of residence, economic position, level of education, sex, and sub-national area. We used four indices to measure this inequality. The four measures are Difference (D), Ratio (R), Population-Attributable Fraction (PAF), and Population-Attributable Risk (PAR). D is an absolute measure representing the difference in BCG immunisation between the most and least disadvantaged groups. A higher D value indicates greater inequality. R is a relative measure representing the ratio of BCG immunisation in the most disadvantaged group to the least disadvantaged group. A value greater than 1 indicates higher BCG immunisation rates in the disadvantaged group. PAF is a relative measure indicating the proportion of BCG immunisation in the total population attributable to inequalities. A positive PAF suggests that reducing inequalities would lead to a decrease in overall BCG immunisation. PAR is a relative measure representing the difference in BCG immunisation between the overall population and the population with the lowest BCG immunisation if the entire population had the same level of BCG immunisation as the lowest group. A higher PAR indicates a greater impact of inequalities on BCG immunisation. Both PAF and PAR are connected to the overall (national) BCG immunisation, as they represent the proportion or difference attributable to inequalities relative to this average. The formulas are displayed below. D and PAR represent absolute inequality measures, whereas R and PAF represent relative measures. D and R serve as basic metrics, whilst PAR and PAF function as more intricate metrics.

$$\:D\:=\:\:BCG\:in\:most\:advantaged-BCG\:in\:most\:disadvantaged$$

$$\:R=\:\frac{BCG\:in\:most\:advantaged}{BCG\:in\:most\:disadvantaged}$$

$$\:PAR=\:BCG\:in\:most\:advantaged-\:\mu\:$$

$$\:PAF=\:\:\frac{PAR}{\mu\:}*100$$

Where $\:\mu\:$ is Sierra Leone鈥檚 national average estimate for BCG immunisation coverage.

The differences between the extremes were given priority for stratifiers with more than two categories. For example, there are differences in educational attainment between those with no schooling and those with secondary or higher education. Similarly, income disparities exist between individuals in the poorest and richest quintiles. Additionally, there are variations in several factors between regions, such as the South and East. The calculations above indicate that the age group 20鈥�49, individuals living in urban areas, those with secondary or higher education, individuals with higher wealth, and individuals residing in the Southern province are the most privileged. The distribution across all subgroups, such as education, wealth, and sub-provinces with more than two categories, was of great interest due to the importance of PAR and PAF.

Ethical consideration

This study did not require ethical clearance because the SLDHS dataset is available to the public. The permission to use the dataset for publication was obtained from the Monitoring and Evaluation to Assess and Use Results Demographic and Health Surveys (MEASURE DHS).

Results

Trends in BCG immunisation coverage among one-year-olds in Sierra Leone by different inequality dimensions, 2008鈥�2019

Table听1 shows the trends in BCG immunization coverage among one-year-olds in Sierra Leone from 2008 to 2019, by various dimensions of inequality: age, economic status, education, place of residence, sex, and region. The BCG immunization coverage increased significantly from 82.0% in 2008 to 96.3% in 2019, indicating a positive trend in vaccination efforts. Children of mothers aged 15鈥�19 years BCG immunisation coverage increased from 86.4% (95% CI: 76.0, 92.7) in 2008 to 91.9% (85.8, 95.5) in 2019. Children of mothers aged 20鈥�49 years BCG immunisation coverage rose from 81.6% (78.1, 84.6) in 2008 to 96.7% (95.2, 97.8) in 2019, showing a substantial increase, particularly in 2013 (95.2%, 93.5, 96.5). Children of mothers in Quintile 1 (poorest) BCG immunisation coverage increased from 78.1% (69.4, 84.9) in 2008 to 94.5% (91.4, 96.5) in 2019. Quintile 2 BCG immunisation coverage increased from 80.3% (73.4, 85.7) in 2008 to 97.2% (94.9, 98.5) in 2019. Quintile 3 BCG immunisation coverage increased from 84.1% (75.9, 89.9) in 2008 to 95.8% (92.6, 97.6) in 2019. Quintile 4 BCG immunisation coverage rose from 82.3% (75.2, 87.7) in 2008 to 99.0% (96.7, 99.7) in 2019. Quintile 5 (richest) BCG immunisation coverage went from 87.4% (80.6, 92.0) in 2008 to 95.8% (86.3, 98.8) in 2019, indicating that even the wealthiest saw improvements. Children of mothers with no education BCG immunisation coverage increased from 78.8% (74.7, 82.5) in 2008 to 96.2% (94.3, 97.4) in 2019. Children of mothers with primary education BCG immunisation coverage rose from 91.0% (84.5, 95.0) in 2008 to 96.4% (93.0, 98.2) in 2019. Children of mothers with secondary or higher Education BCG immunisation coverage was consistently high, starting at 92.9% (86.0, 96.6) in 2008 to 96.6% (94.1, 98.0) in 2019. Children of mothers living in rural areas BCG immunisation coverage increased from 79.6% (75.3, 83.3) in 2008 to 96.1% (94.6, 97.2) in 2019. Children of mothers living in urban areas BCG immunisation coverage increased from 89.0% (83.9, 92.6) in 2008 to 96.8% (92.9, 98.6) in 2019, showing that urban areas had higher coverage throughout the years. Female children BCG immunisation coverage rose from 79.3% (74.7, 83.2) in 2008 to 96.0% (93.4, 97.5) in 2019. Male children BCG immunisation coverage increased from 84.8% (80.3, 88.4) in 2008 to 96.7% (95.3, 97.8) in 2019, indicating males had a higher coverage rate than females in 2008 but converged by 2019. Children of mothers living in the east BCG immunisation coverage increased from 88.6% (80.8, 93.5) in 2008 to 95.1% (91.7, 97.1) in 2019. Children of mothers living in the North increased from 75.2% (68.6, 80.8) in 2008 to 96.4% (93.9, 97.9) in 2019. Children of mothers living in the Northwestern region data was not available for 2008 and 2013, but BCG immunisation coverage reached 96.2% (92.6, 98.0) in 2019. Children of mothers living in the South BCG immunisation coverage rose from 82.6% (76.7, 87.2) in 2008 to 97.4% (95.5, 98.5) in 2019. Children of mothers living in the West BCG immunisation coverage increased from 93.7% (87.7, 96.9) in 2008, and improved to 96.6% (88.0, 99.1) in 2019.

Table 1 Trends in BCG immunisation coverage among one-year-olds in Sierra Leone by different inequality dimensions, 2008鈥�2019

Inequality measures of estimates of factors associated with BCG immunisation coverage among one-year-olds in Sierra Leone, 2008鈥�2019

Table听2 presents inequality measures for factors associated with BCG immunisation coverage among one-year-olds in Sierra Leone from 2008 to 2019. The measures include D, PAF, PAR, and R.听Age-related inequalities between children of听older mothers (20-49) and younger mothers (15-19) increased from a Difference of -4.7 percentage points in 2008 to 4.8听percentage points in 2019. The PAF increased from zero in 2008 to 0.4% in 2019 indicating that the national average of BCG听immunisation coverage would have increased by 0.4% without age-related inequalities. Economic-related inequalities between听children of mothers in Quintile 5 (richest) and Quintile 1 (poorest) decreased from a Difference of 9.2 percentage points in 2008 to听1.2 percentage points in 2019. The PAF decreased from 6.5% in 2008 to zero in 2019 indicating the absence of economic-related听inequality. Educational-related inequalities between children of mothers with secondary/higher education and no education听decreased from a Difference of 14.1 percentage points in 2008 to 0.4 percentage points in 2019. The PAF decreased from 13.3% in听2008 to 0.2% in 2019 indicating that the national average of BCG immunisation coverage would have increased by 0.2% without听educational-related inequalities. Place of residence-related inequalities between children of mothers living in urban areas and rural听areas decreased from a Difference of 9.3 percentage points in 2008 to 0.7 percentage points in 2019. The PAF decreased from听8.5% in 2008 to 0.5% in 2019 indicating that the national average of BCG immunisation coverage would have increased by 0.5%听without place of residence-related inequalities. The sex of the child-related inequalities between male and female children听decreased from a Difference of 5.4 percentage points in 2008 to 0.7 percentage points in 2019. The PAF decreased from 3.3% in听2008 to 0.4% in 2019 indicating that the national average of BCG immunisation coverage would have increased by 0.4% without听sex of the child-related inequalities. Provincial inequalities decreased from a Difference of 18.5 percentage points in 2008 to 2.3听percentage points in 2019. The PAF decreased from 14.3% in 2008 to 1.1% in 2019 indicating that the national average of BCG听immunisation coverage would have increased by 1.1% without provincial inequalities.

Table 2 Inequality measures of estimates of factors associated with BCG immunisation coverage among one-year-olds in Sierra Leone, 2008鈥�2019

Discussion

This study examined the trends and inequalities in BCG vaccination coverage among one-year-olds in Sierra Leone. The analysis of BCG immunisation coverage among one-year-olds in Sierra Leone from 2008 to 2019 reveals significant progress, with overall coverage increasing from 82.0% in 2008 to 96.3% in 2019. Coverage was generally higher for children of older mothers (20鈥�49), wealthier families, and mothers with secondary or higher educations. Urban areas consistently have higher coverage than rural areas, and females have slightly higher coverage than males. Provincially, the South and East have the highest coverage, while the North has the lowest.

BCG immunisation coverage is consistently higher among children of mothers aged 20鈥�49 compared to those of mothers aged 15鈥�19. This difference may be due to older mothers having better access to healthcare information and services or being more experienced in navigating healthcare systems. These findings align with previous research indicating maternal age may influence health-seeking behaviour and access to maternal healthcare, including antenatal care (ANC) [28]. Studies have confirmed the relationship between ANC attendance and health facility deliveries [29], which may subsequently increase BCG vaccination rates as it is the first vaccine the newborn receives. Targeted interventions are needed to ensure high coverage across all maternal age groups.

There are pronounced socioeconomic disparities in BCG immunisation coverage. Children from wealthier quintiles show progressively higher coverage. In contrast, those from the poorest quintile (Quintile 1) consistently have the lowest coverage rates, even though BCG vaccination is free in Sierra Leone. In 2008, the D was at 9.2, highlighting significant inequalities favoring wealthier families. However, this value dropped to -1.2 in 2013, suggesting a temporary improvement in coverage among poorer households, but it rebounded to 1.2 in 2019. The PAF for economic status remained consistent, suggesting that economic factors still play a critical role in determining vaccination coverage. The PAR shows that while the economic status remains a significant determinant, the impact of wealth on coverage has become more pronounced over time, necessitating targeted interventions to address economic disparities. This finding aligns with previous research, indicating that economically disadvantaged households encounter financial and non-financial obstacles in accessing immunisation services. These barriers include transportation expenses to reach health facilities, childcare expenses for other children, and the opportunity cost of taking time off from work [30,31,32]. To mitigate these disparities, strategies could include enhancing outreach and education initiatives in low-income communities, integrating immunisation services with existing social support programs, conducting home visits to reach unvaccinated newborns delivered at home, and facilitating referrals to health facilities [33].

Results of the study show that education level significantly influences BCG immunisation coverage, with children of mothers with higher education more likely to be vaccinated. However, according to the findings, the educational-related inequalities in BCG coverage have declined over the years, indicating a trend towards more equitable access to vaccination services regardless of parental education level. The D showed a decrease from 14.1 in 2008 to 0.4 in 2019, indicating a significant reduction in educational inequalities. This trend suggests that efforts to improve maternal education have positively impacted vaccination rates. The PAF for education also decreased over the years, reflecting a narrowing gap in access to immunization services based on educational attainment. The PAR indicates that while education remains a critical factor, the influence of educational disparities on vaccination coverage has lessened. These results corroborate findings from other studies that emphasize the role of maternal education in child health outcomes [34,35,36,37]. The study conducted in India revealed that mothers with higher levels of education were more likely to have undergone four or more antenatal care (ANC) check-ups. This tendency could indicate a higher likelihood of their children receiving the BCG vaccine since they are more likely to deliver in a health facility [36]. Such mothers might reside in more affluent households, have fewer children, and inhabit areas where antenatal check-ups are more prevalent [34]. Public health initiatives should focus on improving health literacy and providing accessible education to enhance immunisation uptake. Conversely, a recent study in Sierra Leone found no differences in BCG immunisation coverage related to educational attainment [26].

Our findings revealed the presence of urban and rural disparities, which have experienced substantial improvement in BCG immunisation coverage, with more change in urban areas. The D fluctuated from 9.3 in 2008 to -1.2 in 2013, then to 0.7 in 2019. This suggests that urban areas initially experienced a significant advantage in coverage, but rural areas began to catch up, particularly by 2013. However, the slight increase in disparities by 2019 indicates that while progress has been made, urban-rural gaps persist. The PAF remained stable, indicating that residence continues to influence vaccination coverage significantly. The PAR suggests that while urban areas benefit from better healthcare infrastructure, ongoing efforts are needed to strengthen rural healthcare services to ensure equitable access.This is consistent with literature highlighting urban-rural inequality in Southern Ethiopia鈥檚 healthcare access [38]. Urban areas typically benefit from better healthcare infrastructure and services, facilitating higher immunisation rates. Efforts to close the urban-rural gap should include strengthening rural healthcare facilities, training more healthcare workers in rural areas, and ensuring consistent vaccine supply and distribution. UNICEF also reports similar disparities in antenatal care coverage, with at least four visits and the presence of skilled attendants at birth in Sierra Leone, highlighting the broader issue of unequal access to maternal and child healthcare services that can influence BCG vaccination coverage [39]. However, the finding deviates from studies conducted in other areas of Ethiopia, including Tehuledere [40] and Pawi [41].

Another inequality identified in BCG coverage was the sex of the child, though it has narrowed over time. The D for sex indicates a narrowing gap over time, with values of 5.4 in 2008 decreasing to 0.7 in 2019. This suggests that sex-related barriers to immunization are being addressed, leading to more equitable coverage for boys and girls. The PAF remained constant, indicating that while sex disparities exist, their impact on overall coverage has diminished. The PAR reflects a growing trend towards gender equality. Continued focus on sex equality in healthcare access will help maintain and further this progress. Similar findings were found in a systematic review study in Madagascar, where most of the studies reviewed found a slightly higher immunisation rate in boys than girls [42]. As our study found no clear indication of a significant difference in BCG immunisation coverage between boys and girls, in previous studies, sex-related differences were found in earlier studies in Africa, namely Mozambique and the Democratic Republic of the Congo [43].

Additionally, BCG immunisation coverage varies significantly across regions. The South and East regions have the highest coverage, followed by the Northwest and North, with the North consistently having the lowest coverage. The D show values of 18.5 in 2008, decreasing to 5.7 in 2013, and further dropping to 2.3 in 2019. This trend indicates a progressive improvement in coverage across regions, particularly in the South and East, which consistently show higher rates. The PAF and PAR values reinforce the idea that regional factors are critical in determining vaccination coverage, and targeted interventions are necessary to address the persistent gaps in the North. A study by James et al. (2023) [44] found that three in every 20 (15%) Sierra Leonean women chose to give birth to their last child at home in 2019. This statistic is particularly relevant to our analysis, as it highlights a significant proportion of births occurring outside of healthcare facilities. Home deliveries can pose challenges for timely access to immunization services, including BCG vaccination, which is typically administered shortly after birth in health facilities [44]. Regional disparities in vaccination coverage by gender have been documented in one study in India [45]. The missing data for the Northwestern region in 2008 and 2013 limits a comprehensive analysis of trends in that area. However, the consistently lower coverage in the North indicates a need for targeted regional interventions, such as improving healthcare infrastructure, enhancing healthcare worker training, and conducting extensive community outreach programs [46, 47].

Policy and practice implications

The findings on increased national coverage with persistent disparities in Sierra Leone鈥檚 BCG immunisation program suggest several policy and practice implications. The government should develop and implement policies prioritizing equitable access to BCG vaccination for all children, regardless of socioeconomic background, geographic location, age, or sex. This might involve allocating additional resources to areas with lower coverage, such as the North region and the poorest quintile. Consideration could be given to conditional cash transfer programs that incentivize mothers, particularly younger ones, to vaccinate their children. Policies promoting free primary education can indirectly improve BCG coverage by empowering women and potentially increasing awareness about vaccination benefits. Healthcare workers can implement targeted outreach programs in communities with low coverage, focusing on educating mothers and addressing any concerns they might have. Utilizing mobile clinics can improve access to immunisation services in remote areas, particularly the North region. Training and empowering community health workers to raise awareness, dispel myths, and promote BCG vaccination at the local level can be highly impactful. By implementing these policy and practice changes based on the study鈥檚 findings, Sierra Leone can work towards achieving universal and equitable BCG immunisation coverage for all children, ultimately contributing to a healthier future for its citizens.

Strengths and limitations

HEAT is designed to assess inequalities within a population, making it ideal for analyzing disparities in BCG coverage across different sociodemographic groups. HEAT offers various summary measures of inequality, providing a more comprehensive picture of how coverage varies between groups. The Sierra Leone DHS provides data across multiple years (2008鈥�2019), allowing for trend analysis of BCG coverage over time. DHS data is often disaggregated by relevant factors like wealth index, education, and region, enabling analysis of coverage inequalities. While valuable, it has some limitations. HEAT can be complex, requiring technical expertise in data analysis and interpretation. HEAT relies on pre-existing data sets, which might not always capture all relevant factors affecting BCG coverage. HEAT analyses population-level data, and the findings may not translate directly into individual experiences. DHS surveys rely on sampling techniques, and there鈥檚 a possibility of underrepresentation of certain groups. Respondents might inaccurately recall or report vaccination history. DHS data might not capture specific reasons behind vaccination disparities.

Conclusion

The findings indicate a substantial improvement in BCG immunisation coverage in Sierra Leone, among one-year-olds, reflecting听successful public health initiatives. However, age-related inequalities have worsened, with coverage among children of younger听mothers declining relative to those of older mothers, suggesting a need for targeted interventions for this demographic. In contrast,听economic, educational, sex, and place of residence-related inequalities have notably decreased, indicating progress in equitable听access to immunisation across different socioeconomic strata. Additionally, provincial inequalities have decreased significantly, yet听a difference of 2.3 percentage points remains, highlighting the need for continued efforts to ensure that all provinces receive听adequate healthcare resources and outreach. The absence of economic-related inequality by 2019 is particularly encouraging, as it听suggests that economic barriers to immunisation have been effectively addressed. Furthermore, the reduction in educational and听provincial inequalities highlights the effectiveness of strategies aimed at improving access and awareness in underserved areas. The听government and policymakers in Sierra Leone should continue to implement targeted educational campaigns aimed at younger听mothers to improve their awareness and access to immunisation services. Additionally, efforts should be made to address any听lingering gender biases in healthcare access, ensuring that both male and female children receive equal immunization opportunities.听Continued investment in healthcare infrastructure in rural and underserved provinces is essential to eliminate geographical听disparities. Finally, ongoing monitoring and evaluation of immunization coverage across different populations will be crucial to听adapt strategies and ensure equitable health outcomes for all children in Sierra Leone.