The
mRNA vaccine platform has offered the greatest potential in fighting the
COVID-19 pandemic owing to rapid development, effectiveness, and scalability to meet the global demand. There are many other
mRNA vaccines currently being developed against different emerging
viral diseases. As with the current
COVID-19 vaccines, these
mRNA-based
vaccine candidates are being developed for parenteral administration via
injections. However, most of the emerging viruses colonize the mucosal surfaces prior to systemic
infection making it very crucial to target mucosal immunity. Although parenterally administered
vaccines would induce a robust systemic immunity, they often provoke a weak mucosal immunity which may not be effective in preventing mucosal
infection. In contrast,
mucosal administration potentially offers the dual benefit of inducing potent mucosal and systemic immunity which would be more effective in offering protection against mucosal
viral infection. There are however many challenges posed by the mucosal environment which impede successful mucosal vaccination. The development of an effective delivery system remains a major challenge to the successful exploitation of mucosal
mRNA vaccination. Nonetheless, a number of delivery vehicles have been experimentally harnessed with different degrees of success in the mucosal delivery of
mRNA vaccines. In this review, we provide a comprehensive overview of
mRNA vaccines and summarise their application in the fight against emerging
viral diseases with particular emphasis on
COVID-19 mRNA platforms. Furthermore, we discuss the prospects and challenges of
mucosal administration of
mRNA-based
vaccines, and we explore the existing experimental studies on mucosal
mRNA vaccine delivery.