A Study to Evaluate Safety, Reactogenicity and Immunogenicity of GSK Biologicals' RSV Investigational Vaccine Based on Viral Proteins Encoded by Chimpanzee-derived Adenovector (ChAd155-RSV) (GSK3389245A) in Infants

The purpose of this study is to provide critical information on the safety, reactogenicity
and immunogenicity profile of the investigational recombinant chimpanzee adenovirus Type
155-vectored RSV (ChAd155-RSV) vaccine in infants likely to be unexposed to RSV and will
assess a single lower dose and a higher two dose regimen, before moving to future studies.
This study will also assess if there is a risk of 'vaccine-induced enhanced RSV disease'
after vaccination of these infants with the ChAd155-RSV vaccine.