In the trial, the vaccine was administered nasally to healthy adult volunteers to assess safety, tolerability, excretion, and immunogenicity. In preclinical studies, the vaccine showed decreased host cell binding and infectivity. The candidate also protected against replication of wild-type RSV in animal models.

The RSV vaccine live attenuated candidate lacks the G-protein but is still able to produce an effective immune response. It was engineered using reverse genetics to remove the attachment protein from the RSV genome.

RSV is a major cause of lower respiratory tract infections in children and the elderly. The virus accounts for approximately 3.2 million hospital admissions per year worldwide and is a leading cause of death in an estimated 120,000 children under the age of five. A pediatric vaccine against RSV would prevent morbidity and mortality in infants and reduce transmission to the elderly.