A Study to Evaluate the Safety of the Respiratory Syncytial Virus Vaccine MEDI7510 in Older Adults

The purpose of this study is to determine if the administration of single ascending intramuscular doses of the RSV sF antigen or MEDI7510 will be safe and well tolerated in adults 60 years or older who are healthy or who have stable, chronic underlying medical conditions.

A phase 1a, first time in human, double-blind, randomized, placebo-controlled, cohort escalation study evaluating the safety and tolerability of a single ascending intramuscular dose of RSV sF or MEDI7510 or placebo.

Approximately 146 participants will be enrolled at 3 US study centers and randomized in a 5:1 ratio by cohort as described below:

Cohort 1: RSV sF 20 microgram (mcg) (n=20) or placebo (n=4) Cohort 1a: MEDI7510 (20 mcg RSV sF with 2.5 mcg glucopyranosyl lipid A (GLA) + 2% weight per volume stable emulsion (n=20) or placebo (n=4) Cohort 2: RSV sF 50 mcg (n=20) or placebo (n=4) Cohort 2a: MEDI7510 (50 mcg RSV sF with 2.5 mcg glucopyranosyl lipid A (GLA) + 2% weight per volume stable emulsion (n=20) or placebo (n=4) Cohort 3: 80 mcg RSV sF (n=20) or placebo (n=4) Cohort 3a: MEDI7510 (80 mcg RSV sF with 2.5 mcg glucopyranosyl lipid A (GLA) + 2% weight per volume stable emulsion (n=20) or placebo (n=4)

Eligibility Criteria:
Inclusion Criteria:

* Age greater than or equal to 60 years
* Written informed consent and any locally required authorization obtained prior to any protocol related procedures
* Ambulatory or ambulatory with assistance (not institutionalized, bedridden, or homebound
* Weight at or above 110 Pounds (lbs)
* Hemoglobin within normal range for age and gender

Exclusion Criteria:

* History of allergy to any component of the vaccine
* Pregnancy or potential to become pregnant during the study. Females who have had a menstrual period within the 12 months prior to study enrollment or are undergoing any fertility treatment or who plan to undergo fertility treatments during the study period are excluded
* Any unstable chronic medical condition, including one that has resulted in change in therapy (medication or other) in the 30 days prior to randomization or hospitalization in the previous year or might be predicted to result in hospitalization in the year after enrollment. Participant with severe, untreated or uncontrolled underlying medical disease that might either compromise participant safety or affect the ability to assess safety of the investigational product are excluded
* Clinically significant abnormalities in Screening laboratory assessments or Screening electrocardiogram (ECG)
* History of hepatitis B or hepatitis C infection
* Cognitive disorder such that informed consent cannot be obtained directly from the participant
* Previous vaccination against respiratory syncytial virus (RSV)
* History of allergy to eggs in adulthood
* History of or current autoimmune disorder
* Immunosuppression caused by disease, including human immunodeficiency virus (HIV), or medications. Any oral prednisone dosing within 30 days of enrollment or planned dosing within the 360-day follow-up period would disqualify.
* History of splenectomy or of condition affecting splenic function
* History of cancer within preceding 5 years other than treated non-melanoma skin cancer
* Body Mass Index 40 or higher
* Significant infection or other acute illness, including fever over 100 fahrenheit (F) on the day prior to or day of randomization
* Receipt of any nonstudy vaccine within 30 days prior to study dosing or expected receipt of nonstudy vaccine within 30 days after study dosing
* Receipt of any investigational product in the 90 days prior to randomization or expected receipt of investigational product during the period of study follow-up
* Receipt of immunoglobulins or blood products within 4 months of study dosing (120 days) or expected receipt of investigational product during the period of study follow-up
* History of thrombocytopenia or bleeding disorder or use of anticoagulants. Participants receiving drugs with anti-platelet activity such as nonsteroidal antiinflammatory drugs, clopidogrel or aspirin are not excluded
* Expected receipt of antipyretic or analgesic medication on a daily or every other day basis from randomization through 72 hours after receipt of investigational product (IP) \[a daily dose of 163 milligram (mg) or higher is not considered a contraindication to enrollment\]
* Participants who have significant scarring, tattoos, abrasions, cuts, or infections over the deltoid region of both arms that, in the principle investigator's (PI) opinion, could interfere with evaluation of injection site local reactions
* Concurrent enrollment in another clinical study that involves any invasive clinical procedure, including phlebotomy
* History of alcohol or drug abuse or psychiatric disorder that in the PI's opinion would affect the participants safety or compliance with study
* Employees of individuals directly involved with the conduct of the study, individuals who themselves are involved with the conduct of the study, or immediate family members of such individuals.