Microneedle Patches for Vaccine Delivery: A Review of Formulation, Immunogenicity and Distribution Advantages

Microneedle patches are minimally invasive platforms designed to deliver vaccine antigens across the stratum corneum into the epidermal and dermal layers of the skin, where antigen-presenting cells can contribute to the induction of immune responses. This review examines major microneedle configurations, formulation considerations, immunogenicity, and potential logistical advantages relevant to vaccination. Solid, coated, dissolving, and hollow microneedles differ in their mechanisms of antigen incorporation and release. Among these systems, dissolving and coated microneedles have received particular attention for vaccine delivery. Formulation strategies using stabilising excipients such as trehalose and carboxymethylcellulose have been investigated to preserve antigen integrity during fabrication, drying, storage, and administration. Experimental studies with influenza, measles, and several other vaccine antigens have demonstrated humoral and cellular immune responses that can be comparable with conventional vaccination under specific study conditions. Early clinical studies of influenza and measles-rubella vaccines have also provided preliminary evidence of acceptable safety and immunogenicity. Microneedle patches may additionally offer practical advantages, including reduced sharps waste, single-dose presentation, avoidance of vaccine reconstitution, simplified administration, and the possibility of self-administration or administration by minimally trained personnel. However, important limitations remain regarding long-term antigen stability, dose uniformity, reproducible application, manufacturing scalability, sterilisation, and validation in larger and more diverse human populations. Continued clinical and manufacturing research is therefore required before widespread implementation.