The role of engineered materials in mucosal vaccination strategies

Mucosal pathogens, as exemplified by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), human immunodeficiency virus (HIV) and Mycobacterium tuberculosis , lead to substantial morbidity and mortality worldwide and pose serious threats to global health. Mucosal vaccination is crucial to combating mucosal pathogens because it enables the immune system to directly target and neutralize pathogens at their point of entry. Mucosal vaccines need to penetrate the mucus layer, reach the target tissue and activate robust immune responses in the mucosal tissues. Material-based strategies are necessary to meet these requirements. In this Review, we provide an overview of current mucosal vaccines, categorized by administration route, to highlight the importance of material design in overcoming the existing delivery challenges. We discuss the different classes of materials currently being used as vaccine carriers to induce antigen-specific mucosal immunity, including lipids, natural and synthetic polymers, inorganic materials and pathogen-inspired materials.