Rubella and congenital rubella syndrome in the GCC countries: A retrospective ecological analysis of elimination progress and scenario-based projections, 2020-2024.

Introduction: Rubella and congenital rubella syndrome (CRS) remain vaccine-preventable priorities. Although the Gulf Cooperation Council (GCC) countries maintain high routine rubella-containing vaccine (RCV) coverage and well-established immunisation programmes, the region is also characterised by large migrant populations, intense international mobility, and complex population immunity profiles that may sustain vulnerability to rubella transmission even in high-coverage settings. This study assessed progress toward rubella and CRS elimination in the GCC during 2020-2024 and examined the policy implications of the observed patterns. Methods: A retrospective ecological analysis conducted using aggregated country-level rubella surveillance, CRS, and immunization data from the six GCC countries for 2020-2024. Rubella incidence per 1,000,000 population was calculated and compared with the WHO elimination threshold of less than 1 case/1,000,000/year. Scenario-based Poisson regression models projected annual reported cases for 2026-2055 under four vaccination coverage scenarios: baseline, optimistic, pessimistic, and disruption. Results: Bahrain and Oman maintained zero rubella incidence with sustained two-dose coverage of 97-99%. Kuwait reported six total cases (peak incidence: 0.7/1,000,000). Qatar recorded 16 cases in 2023 (incidence: 5.4/1,000,000) despite three consecutive years of 99% two-dose coverage. Saudi Arabia reported 476 total cases (peak incidence: 5.5/1,000,000) despite 96-98% RCV1 coverage. The UAE reported 67 total cases with a persistent non-zero burden. No CRS cases were reported region-wide. Pooled GCC countries rubella incidence did not meet the WHO elimination threshold in any study year, peaking at 4.7/1,000,000 in 2023. Under the optimistic scenario, all countries are projected to reach zero cases by 2040. Conclusions: The GCC countries have achieved substantial rubella control, with two member states demonstrating elimination-consistent epidemiological patterns. However, high childhood coverage alone did not prevent episodic transmission in Qatar, Saudi Arabia, and the UAE, reflecting residual immunity gaps. Sustaining regional elimination requires targeted strategies for adult migrant populations, strengthened active CRS surveillance, and a coordinated regional importation response.