Sex-disaggregated analysis of measles incidence in Sierra Leone

Measles remains a public health challenge in Sierra Leone, a country with a history of socio-economic and health system disruptions. Despite global efforts to control and eliminate measles, regional disparities and systemic challenges persist. This study aimed to assess sex-disaggregated age-standardised incidence rates of measles per 100,000 population, using data extracted from the WHO Health Equity Monitor via the HEAT toolkit, consistent with Global Burden of Disease (GBD) methodology to inform targeted public health interventions. We conducted a sex-disaggregated analysis using data from the World Health Organization (WHO) Equity Database and the Health Equity Assessment Toolkit (HEAT). Age-standardized incidence rates of measles per 100,000 population were calculated for males and females from 2000 to 2021. Key equity metrics, including absolute difference (D), incidence rate ratio (R), population attributable fraction (PAF), and population attributable risk (PAR), were computed to evaluate sex-based disparities in measles burden over the study period. The age-standardised incidence rate declined substantially from 1,908.1 cases per 100,000 population in 2000 to 43.4 cases per 100,000 population in 2021, representing an overall reduction of approximately 97.7%. The incidence rate decreased markedly to 136.5 cases per 100,000 population in 2005, increased to 620.6 and 625.3 cases per 100,000 population in 2010 and 2015, respectively, before declining again by 2021. Sex-disaggregated analysis revealed minimal inequality, with incidence rates of 1,946.2 (95% CI 679.1-4344.0), among females and 1,868.8 (95% CI 654.1-4032.5) among males in 2000, declining to 44.2 (95% CI 26.9-64.3) and 42.6 (95% CI 26.0-62.0), respectively, in 2021. The incidence rate ratio remained constant at 1.0 throughout the study period, while the population attributable fraction ranged from -2.1% to -1.9%, indicating minimal sex-based inequality in measles incidence. Although the age-standardised measles incidence rate declined substantially between 2000 and 2021, temporary increases in 2010 and 2015 indicate that progress remains vulnerable to disruptions in routine immunisation services. Geographic and economic inequalities persisted, whereas sex-based differences were minimal. Strengthening routine immunisation systems and implementing equity-focused strategies targeting underserved populations remain essential for achieving and sustaining measles elimination in Sierra Leone.