A Study to Assess the Safety of Live Intranasal Sendai Virus Vaccine in Children and Toddlers

Inclusion Criteria; Parent or legal guardian willing and able to give informed consent and comply with study requirements Child is greater than or equal to one year of age and less than six years of age Adequate blood, liver and kidney function Has not or will not receive other vaccinations within 30 days of receiving study vaccine Exclusion Criteria: History of allergy to eggs or gentamicin History of lung disease, asthma, and hospitalization for respiratory illness, immunodeficiency, sickle cell disease, or any other serious underlying condition Children who have a family history of primary immunodeficiency or lack history of maternal or paternal immune status Height or weight less than 5th percentile Upper respiratory tract infection (URI) or household member with URI Evidence of developmental delay or evolving neurological disorders Household member or daycare contact (i.e. stay in the same room in daycare) less than 24 months of age if same room contact is expected within 14 days of vaccination or 7 days after booster, or prior to evidence of vaccine clearance Immunodeficient household members or other close contacts if same room contact is expected within 14 days of vaccination or 7 days after booster, or prior to evidence of vaccine clearance Current use of investigational or immunosuppressive drugs (e.g., steroids) Current use of antibiotics or antivirals