Typhoid fever remains a significant health problem in sub-Saharan Africa, with incidence rates >100 cases per 100,000 person-years of observation. Despite the prequalification of safe and effective typhoid conjugate vaccines (TCV), the uptake of these vaccines in African countries has remained low. Real-life effectiveness data, which inform public health programs on the impact of TCVs in reducing typhoid-related mortality and morbidity, are critical to enhancing the introduction of TCVs in high-burden settings. Here we describe a cluster-randomized trial to investigate population-level protection of TCV against blood culture-confirmed typhoid fever. A total of 80 geographically distinct clusters have been delineated within the Agogo district of the Asante Akim region in Ghana. Clusters will be randomized to the intervention arm receiving TCV or a control arm receiving the meningococcal A conjugate vaccine. The primary study endpoint is the overall protection of TCV against blood culture-confirmed typhoid fever. Total, direct, and indirect protection will be measured as secondary outcomes. Blood culture-based enhanced surveillance will enable the estimation of incidence rates in the intervention and control clusters. Evaluation of the real-world impact of TCVs will improve uptake of prequalified/licensed safe and effective typhoid vaccines in public health programs of high burden settings.
A cluster-randomised controlled Phase IV trial (cRCT) assessing the impact of a Vi-Polysaccharide conjugate vaccine in preventing typhoid infection in Asante Akim, Ghana (TyVEGHA) with a primary endpoint of determining the total protection conferred by single-dose vaccination with Vi-TT against blood culture-confirmed symptomatic S. Typhi infection in the intervention vaccine clusters, compared with the control vaccine clusters.