Safety and immunogenicity of the Ad26/protein preF RSV vaccine in adults aged 18 to 59 years with and without at-risk comorbidities for severe respiratory syncytial virus disease: A phase 3, randomized, controlled, immunobridging trial.

Background: Respiratory syncytial virus (RSV) causes a significant disease burden in adults with chronic comorbidities. Rates of severe RSV disease and death are as high, or higher in younger adults with risk factors than in healthy older adults in whom RSV vaccination is recommended. We conducted an immunobridging study using the Ad26/protein RSV preF vaccine, which previously demonstrated efficacy in adults aged ≥65 years to support extrapolation of efficacy demonstrated in an older population to younger adult populations at high risk of severe RSV disease.