Mechanisms of Norovirus Immunity: Implications for Vaccine Design.

Human noroviruses are the predominant cause of acute gastroenteritis globally, causing significant morbidity and mortality especially in low- and middle-income countries. Despite this immense public health burden, there are no commercially available vaccines or antiviral drugs, highlighting a critical unmet medical need. Norovirus vaccine development faces several challenges including extensive viral diversity and limited mechanistic understanding of protective immunity. While several vaccine candidates-including virus-like particle, adenovirus-vector, and mRNA-lipid nanoparticle vaccines-are in clinical trials, none have achieved complete protection in adults or demonstrated efficacy in young children. Understanding the mechanisms underlying norovirus immunity and the relative importance of mucosal responses remains crucial for vaccine optimization. Continued research addressing these basic questions, along with strategic antigen selection and platform optimization, are essential to overcome current limitations to the development of broadly protective norovirus vaccines.