Abstract
<title>Abstract</title> <p> <bold>Background:</bold> The effectiveness of vaccines, which is crucial for successful vaccination programs, depends on a reliable cold chain. However, in resource-limited regions characterized by high temperatures, the cold chain's integrity can be compromised by unreliable energy supplies and inadequate operational oversight, thereby weakening vaccine performance. Northern State, Sudan, faces significant environmental and infrastructural challenges. Therefore, a thorough evaluation of cold chain operations, using internationally recognized standards, is necessary. <bold>Methods:</bold> A facility-based cross-sectional study was conducted to assess the operational performance of the vaccine cold chain system in Northern State, Sudan. This assessment used the World Health Organization's Effective Vaccine Management Assessment (EVM) framework. The study, conducted from November 2024 to February 2025, included all vaccine cold chain locations in Northern State, totaling seventy-four sites. Data were collected through structured interviews, direct observation, and a review of cold chain records, all guided by a WHO-approved EVM assessment tool. A descriptive analysis, using frequencies and percentages, was then done to evaluate how well the system performed compared to WHO standards. <bold>Results:</bold> The study's findings indicated strong performance across critical EVM areas, as Staff were present at 90.5% of the facilities, working equipment was available at 100%, and temperature was recorded twice daily at 93.2%.. In particular, the energy supply proved insufficient; stable electricity was available in only 62.2% of the facilities, voltage regulators were present in 79.7%, backup generators were accessible in 25.7%, and the use of solar energy was minimal (5.4%). The data showed that a significant portion of the equipment, specifically 37.8%, hadn't seen any maintenance in more than a year. Distribution methods were also not ideal, as only 37.8% of the deliveries used refrigerated vehicles, while 62.2% relied on cold boxes. Furthermore, the application of sophisticated temperature monitoring instruments was limited, encompassing shipment loggers (40.5%), electronic thermometers (64.9%), and circular thermometers (77.0%). <bold>Conclusion</bold> : Although the cold chain system generally adheres to WHO-EVM standards, bolstering energy resilience, refining maintenance protocols, and broadening the application of contemporary temperature monitoring technologies are crucial for augmenting system dependability and long-term viability </p>