MUCOSAL VACCINES AND NEEDLE-FREE IMMUNISATION

Conventional injectable vaccines have transformed infectious-disease prevention, but they do not always generate strong immune responses at the mucosal surfaces through which many pathogens enter the body. Mucosal vaccination aims to place vaccine antigens at or near these portals of entry and can stimulate local secretory IgA, tissue-resident cellular responses and systemic immunity. At the same time, needle-free and non-invasive delivery approaches can reduce pain and needle-related waste, simplify administration and potentially improve acceptability and access. Recent research has expanded the field from traditional oral and intranasal formulations toward nanoparticles, lipid-based carriers, chitosan systems, virus-like particles, nucleic-acid platforms, thermostable formulations, dissolving films and other advanced delivery technologies.[1–5] This review examines the immunological basis of mucosal vaccination, major administration routes, formulation and delivery strategies, needle-free technologies, adjuvants, barriers to translation and future opportunities. Particular attention is given to the pharmaceutical challenges of protecting antigens from degradation, overcoming mucus and epithelial barriers, achieving adequate residence time and inducing effective immunity without excessive inflammation. The review also discusses the importance of thermostability, scalable manufacturing, safety, dose consistency, regulatory evaluation and validated correlates of mucosal protection. Mucosal vaccination should not be viewed simply as a replacement for injections; rather, it represents a complementary platform capable of tailoring immunity to the site of pathogen entry. The next generation of vaccine delivery is likely to combine immunology, formulation science, biomaterials, nanotechnology and device engineering to create safer, more accessible and potentially more effective vaccination systems.