Treatments will comprise a single IM dose of a placebo or RSV-F protein nanoparticle vaccine on Day 0, with concurrent IM immunization with a licensed inactivated influenza vaccine. A rescue dose of the licensed TIV will be provided to subjects in all groups except the placebo group on Day 28, the placebo group will receive saline. For each subject, study follow-up will span approximately one year from the first immunization (on Day 0) for all subjects.