 The goal of this study is to evaluate the safety, tolerability and immunogenicity of ascending doses of adjuvant in combination with a single dosage level of RSV sF in adults 60 years or older who are healthy or who have stable, chronic underlying medical conditions. This study will also provide preliminary safety and immunogenicity data to support concurrent dosing of MEDI7510 with influenza vaccine IIV, and to assess the safety of MEDI7510 at a dose previously assessed in the Phase 1a study. 