Nasal vaccines: solutions for respiratory infectious diseases.

Nasal vaccines induce pathogen-specific dual protective immunity at mucosal surfaces and systemically throughout the body. Consequently, nasal vaccines both prevent pathogen invasion and reduce disease severity. Because of these features, nasal vaccines are considered to be a next-generation tool for preventing respiratory infectious diseases, including COVID-19. However, nasal vaccines must overcome key safety concerns given the anatomic proximity of the central nervous system (CNS) via the olfactory bulbs which lie next to the nasal cavity. This review summarizes current efforts to develop safe and effective nasal vaccines and delivery systems, as well as their clinical applications for the prevention of respiratory infections. We also discuss various concerns regarding the safety of nasal vaccines and introduce a system for evaluating them. Nasal vaccines induce protective immunity that prevents the invasion of pathogens from mucosal surfaces and inhibits severe disease. Nasal vaccines are particularly appropriate for respiratory infectious diseases because of their specialized induction of effective immunity in the upper and lower respiratory tracts. Many types of nasal vaccines and delivery systems have been developed worldwide, with those to combat COVID-19 at the top of the list. Unlike conventional vaccines, nasal vaccines are needle-free, thus simplifying immunization procedures and reducing apprehension among vaccinees. To address one particular safety concern regarding nasal vaccines, post-immunization deposition of vaccine antigen in the central nervous system (including the brain) should be monitored. [ABSTRACT FROM AUTHOR]