Feasibility of aerosol vaccination in humans

The feasibility of using aerosol vaccines to achieve mass and rapid immunization, especially in developing countries and disaster areas, is being assessed on the basis of current available information. The aerosol mode of vaccine introduction, which best follows the natural route of many infections, may first lead to development of immunity at the portal of entry, and may also induce a more generalized defense. The recommended optimal way of introducing an aerosol vaccine is nasal breathing, which is more suitable for geriatric and pediatric populations, permits use of greater antigen volumes, and allows easier monitoring of results. Technical requirements for ideal aerosol vaccines and delivery systems, possible adverse effects, and cost-effectiveness are other issues addressed. Several thousand human subjects have been aerosol-vaccinated over a period of many years in Russia with live-attenuated strains against many diseases. Extensive field trials in South America with aerosolized live-attenuated measles vaccine have also been successful, and excellent results have been reported with pilot projects employing inactivated or live-attenuated aerosol influenza A vaccine. We conclude that aerosol immunization seems a promising method of vaccination. Although some basic information is still lacking, this method has already been used successfully in large populations and has therefore passed the phase of initial feasibility evaluation.