Current progress in pulmonary delivery of measles vaccine

Due to the high infectivity of measles virus, achieving sufficient population immunity to interrupt transmission requires two doses of live attenuated measles virus vaccine. Subcutaneous delivery of vaccine by injection requires trained personnel, maintenance of a cold chain and safe disposal of used needles and syringes. Pulmonary vaccine delivery offers the opportunity for cost-savings and improved coverage, but requires re-licensure. Two aerosol vaccine formulations, nebulized liquid and dry powder, and multiple delivery devices have been evaluated in humans and macaques. Nebulized liquid vaccine is effective for a second dose of vaccine in older children, but less effective for primary vaccination of infants. Dry powder vaccine provides solid protection in macaques and boosts responses in immune adults, but has not yet been tested in infants.