Epidemiology of Rubella Virus in a Fragile and Conflict-affected Setting - A Retrospective Analysis of 11 Years Case-based Data in South Sudan.

Introduction: Since establishing routine immunization services in what was then known as Sudan in 1974, South Sudan has not yet introduced the rubella-containing vaccine into its national immunization schedule. This study aims to assess the burden of rubella infection within the existing measles case-based surveillance framework to provide evidence supporting advocacy for introducing the rubella-containing vaccine into the national immunization program. Methods: This study conducted a retrospective descriptive analysis of rubella infection using measles case-based surveillance data from 2013 to 2023. Data were analyzed with descriptive statistics and logistic regression using Epi Info, version 7. Results: During the study period, 17,987 suspected measles cases were reported, with 4944 serum samples collected. Of these, 2083 (42.1%) were positive for measles immunoglobulin M antibodies. Among 2861 samples that tested negative or indeterminate for measles, 678 (23.7%) tested positive for rubella immunoglobulin M antibodies. The study observed a significant increase in rubella positivity rates from 1.6% in 2014 to 34.4% in 2020. Logistic regression analysis showed that rubella infection was significantly more likely among children aged 5-9 years (odds ratio [OR] = 2.234; 95% confidence interval [CI]; 1.468-3.473, Conclusions: The study identified a high prevalence of rubella among young children, particularly those aged 1-9 years and in urban areas, highlighting the need for targeted vaccination strategies. These findings strongly support introducing the rubella vaccine into the national immunization program.