Rubella Epidemiology in South Sudan: 11-Year Retrospective Surveillance Analysis

Overview

This retrospective study analyzed 11 years of measles surveillance data from South Sudan, revealing a rising burden of rubella infections, particularly among children aged 1–14 years. The findings highlight significant rubella circulation in the absence of a rubella vaccine, supporting urgent introduction of rubella-containing vaccines into the national immunization program.

Background

Rubella is a vaccine-preventable viral infection that is generally mild in children but can cause severe congenital defects if contracted during pregnancy. Despite the availability of an effective vaccine, South Sudan has not yet introduced rubella vaccination into its national schedule. The country uses a combined measles-rubella surveillance system, testing measles-negative samples for rubella IgM antibodies. Limited epidemiological data from conflict-affected settings like South Sudan impede informed vaccination policy decisions.

Data Highlights

Key Findings

• Rubella IgM positivity was 23.7% among measles-negative or indeterminate samples.
• Rubella positivity increased significantly from 1.6% in 2014 to 34.4% in 2020.
• Children aged 5–9 years had the highest odds of rubella infection (OR = 2.234), followed by ages 10–14 (OR = 2.101) and 1–4 years (OR = 1.733), compared to infants under 1 year.
• Rubella infection was slightly more common in urban areas than rural (OR = 1.139).
• Rubella cases showed clear seasonality, peaking between December and March.
• The absence of rubella vaccination contributes to ongoing virus circulation and risk of congenital rubella syndrome.

Clinical Implications

The high prevalence of rubella among young children and its increasing trend underscore the urgent need to introduce rubella-containing vaccines into South Sudan's national immunization program. Targeted vaccination strategies focusing on children aged 1–14 years, especially in urban settings, could reduce rubella transmission and prevent congenital rubella syndrome. Enhanced surveillance should continue to monitor vaccine impact post-introduction.

Conclusion

This study provides compelling epidemiological evidence of substantial rubella virus circulation in South Sudan, particularly among children, supporting the critical need for rubella vaccine introduction to prevent congenital rubella syndrome and reduce disease burden.

References

1. WHO/UNICEF Estimates and Surveillance Protocols (2011–2023) -- Rubella and Measles Surveillance in South Sudan