Department of Biological Sciences
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Item Trends and inequalities in BCG immunisation coverage among one-year-olds in Sierra Leone, 2008–2019(BioMed Central, 2024-11-30) Osborne, AugustusBACKGROUND: Bacillus Calmette-Guérin (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's Health Equity Assessment Toolkit (WHO's 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%). Age-related inequalities between children of older mothers (20-49) and younger mothers (15-19) increased from a 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 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) decreased from a Difference of 9.2 percentage points in 2008 to 1.2 percentage points in 2019. Educational-related inequalities between children of mothers with secondary/higher education and no education 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 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 of residence-related inequalities between children of mothers living in urban areas and rural areas decreased from a Difference 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 indicating that the national average of BCG immunisation coverage would have increased by 0.5% without place of residence-related inequalities. The sex of the child-related inequalities between male and female children 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 2008 to 0.4% in 2019 indicating that the national average of BCG immunisation coverage would have increased by 0.4% without sex of the child-related inequalities. Provincial inequalities decreased from a Difference of 18.5 percentage points in 2008 to 2.3 percentage points in 2019. The PAF decreased from 14.3% in 2008 to 1.1% in 2019 indicating that the national average of BCG 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, reflecting successful public health initiatives. However, age-related inequalities have worsened, with coverage among children of younger mothers declining relative to those of older mothers, suggesting a need for targeted interventions for this population. In contrast, economic, educational, sex, and place of residence-related inequalities have notably decreased, indicating progress in equitable access to immunisation across different socioeconomic strata. Additionally, provincial inequalities have decreased significantly, yet a difference of 2.3 percentage points remains, highlighting the need for continued efforts to ensure that all provinces, receive adequate healthcare resources and outreach. The absence of economic-related inequality by 2019 is particularly encouraging, as it suggests that economic barriers to immunisation have been effectively addressed. Furthermore, the reduction in educational and provincial inequalities highlights the effectiveness of strategies aimed at improving access and awareness in underserved areas.Item Inequalities in measles immunization coverage among two-year-olds in Sierra Leone, 2008–2019(BioMed Central, 2024-11-11) Osborne, AugustusBACKGROUND: Measles, a highly contagious and potentially fatal disease, remains a significant public health concern, particularly in low- and middle-income countries. Vaccination is the most effective way to prevent measles and achieving high immunization coverage is crucial for protecting children and communities. This study investigated the trends and inequalities in measles immunization coverage among two-year-olds in Sierra Leone between 2008 and 2019. METHODS: The study utilized data from the Sierra Leone Demographic Health Surveys conducted in 2008, 2013, and 2019. The World Health Organisation Health Equity Assessment Toolkit was used to calculate various inequality measures, including Difference (D), Ratio (R), Population Attributable Risk (PAR), and Population Attributable Fraction (PAF). An inequality assessment was conducted for six stratifiers: age, economic status, level of education, place of residence, sex of the child, and sub-national province. RESULTS: In Sierra Leone, measles immunization coverage increased between 2008 and 2013 and decreased slightly in 2019. In 2008, 66.2% of two-year-olds were immunized, which increased to 86.2% in 2013 and then fell slightly to 82.2% in 2019. There was a decrease in inequality for age from 4.2 percentage points in 2008 to 3.0 percentage points in 2019 (D = 4.2 in 2008 and 3.0 in 2019). Economic-related inequality decreased from 8.1 percentage points in 2008 to 7.5 percentage points in 2019 (D = 8.1 in 2008 and 7.5 in 2019). Inequality in education decreased from 10.3 percentage points in 2008 to 7.4 percentage points in 2019 based on results from the inequality measure D. For place of residence, inequality decreased from 6.0 percentage points in 2008 to 4.0 percentage points in 2019. For the child's sex, the inequality increased from 1.9 percentage points in 2008 to 4.5 percentage points in 2019. The PAF revealed that the setting average could have been 1.4% higher in 2008 and 2.7% higher in 2019 without the child's sex inequality. Provincial inequality decreased from 19.4 percentage points in 2008 to 16.9 percentage points in 2019 (D = 19.4 in 2008 and 16.9 in 2019). CONCLUSION: The observed fluctuations in national measles immunization coverage for children under two underscore the need for sustained efforts in vaccination programs. While improvements in access based on age, socioeconomic status, education level, and place of residence suggest progress in reducing inequalities, the persistent provincial disparities, with a significant gap in 2019, highlight ongoing challenges that must be addressed to ensure equitable health outcomes. Additionally, the increase in inequalities based on the child's sex during the study period raises concerns about targeted interventions that may inadvertently neglect specific groups. These findings imply that policymakers must prioritize strategies that maintain high vaccination rates and focus on closing the geographical and sex-based gaps, particularly in underserved provinces and among vulnerable populations.Item Trends and inequalities in full immunisation coverage among one-year-olds in Sierra Leone, 2008–2019(BioMed Central, 2025-04-23) Osborne, AugustusBACKGROUND: Full immunisation of children by their first birthday is a crucial public health target. Vaccines protect children from preventable diseases, promoting individual and community health. In Sierra Leone, a country with a history of high childhood mortality rates, achieving full immunisation coverage is a critical step towards a healthier future. This study examined the trends and inequalities in full immunisation coverage among children aged one year in Sierra Leone from 2008 to 2019. METHODS: Three rounds of the Sierra Leone Demographic and Health Survey (2008, 2013, and 2019) were analysed. A descriptive approach was adopted for the analysis. Simple \[difference (D) and ratio (R)\] and complex \[population attributable risk (PAR) and population attributable fraction (PAF)\] measures of inequalities were computed using the World Health Organization's Health Equity Assessment Toolkit (WHO's HEAT) software. The measures were computed separately for each of the three surveys, and their estimates were compared. RESULTS: The findings revealed that full immunisation coverage for one-year-olds in Sierra Leone increased significantly between 2008 (40.1%) and 2013 (68.3%). However, there was a decrease in coverage in 2019 (56.5%). Region-related inequalities were the largest and increased slightly between 2008 (D = 13.8; R = 1.4; PAF = 17.8, PAR = 7.1) and 2013 (D = 20.7.; R = 1.3; PAF = 14.2, PAR = 9.7) but decreased in 2019 (D = 18.2; R = 1.3; PAF = 15.3, PAR = 8.6). Substantial education-related inequalities were observed in 2008 (D = 10.1, R = 1.2, PAF = 19.4, PAR = 7.7), but this decreased in 2013 (D = 6.7, R = 1.1, PAF = 8.0, PAR = 5.4; and 2019 D = 5.0, R = 1.0, PAF = 4.7, PAR = 2.4). The age and sex of the child appeared to have minimal influence on the overall inequality in immunisation coverage. CONCLUSION: The study highlights education and region as key contributors to the inequalities. Mothers with lower education were less likely to get their children fully immunised. Immunisation coverage varies significantly across regions, with the Eastern region leading and the Northern region lagging. Age and sex have minimal impact. The government and partner organisations in Sierra Leone should focus outreach programs on these high-risk groups, implement geographically targeted strategies and invest in education and improve access to healthcare facilities. Ensuring vaccine availability, trained personnel, and data collection for monitoring could be useful. There is also the need to develop targeted interventions for regions with lower coverage. These steps are crucial to achieving universal immunisation coverage. TRIAL REGISTRATION: Registration was not necessary since we analysed a secondary dataset.