A Study to Learn About Two or More Vaccines That Are Put Together as One Shot Against Infectious Lung Illnesses, Including COVID-19 and Respiratory Syncytial Virus (RSV).

The purpose of the study is to learn about the safety and effects of a combined vaccine for RSV and COVID-19 when given with a seasonal flu vaccine or when given alone. A combined vaccine will help to reduce the number of vaccinations given when trying to prevent respiratory infections. This study is seeking participants who: * are 65 years of age or older. * are healthy or have well-controlled chronic conditions. * in the past have received at least 3 US-authorized mRNA COVID 19 vaccines, with the most recent vaccine being an updated booster vaccine given at least more than or equal to 150 days before Visit A101 (Day 1). * have not had a flu shot in the last 120 days. * agree to be present for all study visits, procedures, and blood draws. Participants will be involved in this study for 6 months. During this time, participants will have 2 study visits at the study clinic and a 6-month telephone contact.