Increasing the time of exposure to aerosol measles vaccine elicits an immune response equivalent to that seen in 9-month-old Mexican children given the same dose subcutaneously.

Background: A 30-second aerosol measles vaccination successfully primes children 12 months of age and older but is poorly immunogenic when given to 9-month-old children. We examined the immune responses when increasing the duration to aerosol exposure in 9-month-olds.

Methods: One hundred and thirteen healthy 9-month-old children from Mexico City were enrolled; 58 received aerosol EZ measles vaccine for 2.