Patient description: A 67-year-old healthy woman came to the clinic to have her flu shot in early October. She works at a rehab center and has no underlying disease. It is her first vaccination this year. she is menopausal and has 4 children. She does not some. She takes daily multivitamins and anti-hypertensive drugs. She exercises regularly for 30 minutes a day at least 5 days a week. She has no allergies to any food or drugs.

Clinical trial eligibility criteria: eligible ages (years): 55.0-999.0,  Respiratory Syncytial Virus Infections (Main study): 1. Male and female subjects, ≥ 55 years of age. 2. Prior to performance of any trial specific procedures, the subject has read, signed and dated an informed consent form, having been advised of the risks and benefits of the trial in a language understood by the subject, and has signed the Health Insurance Portability and Accountability Act (HIPAA) authorization form. 3. Subjects without symptomatic cardiopulmonary and/or metabolic disease. Note that subjects who have any active symptoms related to cardiac and/or pulmonary and/or metabolic disease (including e.g. uncontrolled asthma, angina pectoris, hyperglycaemia or other episodic symptoms), or who receive ongoing therapy to control current, active symptoms, are not eligible. Subjects on stable treatment (no change in ≥ 1 month) for previous and controlled symptoms or conditions are eligible. The following are examples of subjects who may bear cardiopulmonary or metabolic diagnoses but who would remain eligible Subjects on stable (no change in ≥ 1 month) therapy for findings (e.g. hypertension, hyperlipidemia) which are not associated with current symptoms or disability Subjects with type II diabetes mellitus are considered eligible as long as they are stable on oral antidiabetics and have either a documented glycated hemoglobin (HbA1c) of ≤ 8 % within three months prior to trial participation or confirmation of controlled blood glucose level must be obtained at the SCR (screening) visit by a lab test Subjects who receive short term treatment for temporary conditions Other clinically insignificant findings not deemed to be associated with increased risk for respiratory viral infections as determined by the investigator. 4. Able to comply with trial requirements; including access to transportation for trial visits. 5. Body mass index (BMI) ≥ 18.5 and ≤ 39.9 BMI formula for pounds and inches: BMI = (bodyweight in pounds) * 703 (bodyheight in inches)2 6. Women of childbearing potential (WOCBP) must have used an acceptable method of contraception for at least 30 days prior to the first vaccination, must agree to use an acceptable method of contraception (as defined in Section 8.2.11) during the trial, and must avoid becoming pregnant for at least 28 days after the last vaccination. WOCBP must have a negative serum pregnancy test at screening and a negative urine pregnancy test prior to each vaccination 7. Not clinically significant laboratory values as defined in the protocol, excluding any Grade ≥ 3 toxicity. 8. Negative human immunodeficiency virus antibody test (anti-HIV), negative hepatitis B surface antigen (HBsAG) and negative antibody test to hepatitis C virus. 9. Electrocardiogram (ECG) without clinically significant acute findings (e.g. findings suggestive of current ischemia, ventricular arrhythmias, congestive heart failure and ventricular hypertrophy)  (Main Study): 1. Pregnant or breast-feeding women. 2. Uncontrolled serious infection, i.e. not responding to antimicrobial therapy. 3. History or current clinical manifestation of any serious medical condition, which in the opinion of the investigator would compromise the safety of the subject or would limit the subject's ability to complete the trial History of cerebrovascular disorders, including stroke. Patients with history of transient ischaemic attack (TIA) ≥ 1 year prior to trial participation remain eligible History of myocardial infarction within ≤ 1 year prior to trial participation, current clinical manifestation of angina pectoris, current clinical manifestation of congestive heart failure ≥ New York Heart Association (NYHA) Grade II, uncontrolled high blood pressure defined as systolic blood pressure ≥ 150 mmHg and/or diastolic ≥ 100 mmHg within the last 2 months. 4. History of or active autoimmune disease. Persons with vitiligo or thyroid disease taking thyroid replacement are not excluded. Persons with rheumatoid arthritis not requiring immunomodulatory and/or immunosuppressant treatment are not excluded. 5. Known or suspected impairment of immunologic functions including, but not limited to chronic inflammatory bowel disorders, diabetes mellitus type I. 6. History of malignancy other than squamous cell or basal cell skin cancer, unless there has been surgical excision at least 6 months ago that is considered to have achieved cure. Subjects with history of skin cancer should not be vaccinated at the previous tumor site. 7. Clinically significant mental disorder, not adequately controlled by medical treatment. 8. Active or recent (within the time period of six months before trial participation) history of chronic alcohol abuse and/or intravenous and/or nasal drug abuse. 9. History of allergic disease or reactions likely to be exacerbated by any component of the vaccine, e.g. tris(hydroxymethyl)-amino methane, chicken embryo fibroblast proteins, gentamycin. 10. Known allergy to eggs or aminoglycosides. 11. History of anaphylaxis or severe allergic reaction to any vaccine. 12. Having received any vaccinations or planned vaccinations with a live vaccine within 30 days prior to or after trial vaccination. 13. Having received any vaccinations or planned vaccinations with an inactivated vaccine within 14 days prior to or after trial vaccination. 14. Chronic systemic administration (defined as more than 14 days) of > 5 mg prednisone (or equivalent)/day or any other immune-modifying drugs during a period starting from three months prior to first administration of the trial vaccination and ending at the last visit of the active trial phase. The use of topical, inhaled, ophthalmic and nasal glucocorticoids is permitted. 15. Administration or planned administration of immunoglobulins and/or any blood products during a period starting from three months prior to first administration of the trial vaccination and ending at the last visit of the active trial phase. 16. Use of any investigational or non-registered drug or vaccine other than the trial vaccine within 30 days preceding the first trial vaccination, or planned administration of such a drug between participation in the trial and until 4 weeks after last trial vaccination. 17. Previous or planned vaccination with a RSV vaccine/vaccine candidate. 18. Clinical trial personnel working on the current trial. (Substudy): 1. Prior to performance of any booster substudy specific procedures, the subject has read, signed and dated an informed consent form, having been advised of the risks and benefits of the trial in a language understood by the subject. 2. Subject has completed all vaccinations of the main trial according to protocol (Substudy): 1. Any condition that, in the opinion of the investigator, makes it unsafe for the subject to receive a further vaccination. 2. Pregnancy. 3. An anaphylactic reaction following the administration of any vaccine(s). 4. Clinical need for concomitant or ancillary therapy not permitted in the trial as outlined in Protocol Section 8.2.2. 5. Having received any vaccinations or planned vaccinations with a live vaccine within 30 days prior to or after booster vaccination. 6. Having received any vaccinations or planned vaccinations with an inactivated vaccine within 14 days prior to or after booster vaccination. 7. Chronic systemic administration (defined as more than 14 days) of > 5 mg prednisone (or equivalent)/day or any other immune-modifying drugs during a period starting from 3 months prior to administration of the booster vaccine and ending at the last visit of the booster active trial phase. The use of topical, inhaled, ophthalmic and nasal glucocorticoids is permitted. 8. Administration or planned administration of immunoglobulins and/or any blood products during a period starting from 3 months prior to administration of the booster vaccine and ending at the last visit of the booster active trial phase. 9. Use of any investigational or non-registered drug or vaccine other than the trial vaccine within 30 days preceding the booster vaccination, or planned administration of such a drug during participation in the booster substudy and until 4 weeks after booster vaccination. 10. Subject's request to discontinue 11. Subject's refusal to receive booster vaccination. 12. Subject unwilling or unable to comply with trial requirements. Any reason that, in the opinion of the investigator contradicts administration of the booster vaccination or otherwise requires early discontinuation of a subject