The Impact of Norovirus on Children and Adolescents: Implications for Ongoing Vaccine Development.

Purpose of Review: This article highlights the heightened vulnerability of children and adolescents to norovirus infection and discusses the implications for ongoing vaccine development efforts. Recent Findings: Young children remain highly vulnerable to norovirus infections and are at an increased risk of severe disease. However, a recent Phase 2b clinical trial in infants failed to demonstrate meaningful protection or other clinical benefits. Similarly, low protective efficacy was observed in adults in a separate Phase 2b clinical evaluation, raising concerns about the complexity of norovirus vaccine development, particularly for young children. Summary: Norovirus continues to pose a significant global health threat, affecting individuals of all ages and contributing to considerable morbidity, mortality, and socioeconomic burden. Children and adolescents are especially vulnerable, as they often spend time in closed or semi-closed environments such as daycare centers and schools, settings commonly associated with norovirus outbreaks. The lack of an FDA-approved norovirus vaccine underscores the urgent need for effective preventive strategies. Several vaccine candidates, utilizing diverse platforms, have advanced to Phase 2 clinical trials and beyond, targeting various age groups. While some have shown promise in adults, a recent Phase 2b clinical trial of a VLP-based vaccine in infants failed to demonstrate sufficient efficacy, and another Phase 2b study of an adenovirus-vectored vaccine reported low efficacy in adults. These findings suggest that novel approaches and strategies may be required to overcome the current challenges in norovirus vaccine development.