Entolimod on Immunosenescence in Healthy Geriatric Subjects Receiving Influenza Vaccination

Inclusion: * Men and women of age 65 years and older at the time of enrollment * Eligible to receive Fluzone High-Dose * Female subjects must be past menopause and not pregnant * No history of anaphylactic reaction to gelatin, neomycin, or other vaccine component * Must not have had the flu vaccine within the past 90 days * Medically stable with no exacerbations or changes in medication regimen for chronic diseases in the past 3 months and no hospitalizations in the past 6 months * Must be able to read/write English in order to provide informed consent and comply with study procedures * Expected to be available for the duration of the study Exclusion: * Receipt of any other vaccines within the past 30 days prior to enrollment * Acute illness within the last 7 days * History of hypersensitivity to the flu vaccine or its components (including gelatin, formaldehyde, octoxinol, thimerosal, and chicken protein). * History of Guillain Barré syndrome (GBS) * History of bleeding disorders * Medical contraindication to treatment with vaccine as indicated by a history of autoimmune disease, immune deficiency, or hypersensitivity to other vaccines. * Unstable major cardiovascular, renal, endocrine, immunological or hepatic disorder * Systolic blood pressure (SBP) \< 110 mmHg or orthostatic hypotension \[\>20 mmHg fall in SBP or \>10 mmHg fall in diastolic blood pressure (DBP) with standing\] at the time of screening. * Evidence of an ongoing systemic bacterial, fungal, or viral infection (including upper respiratory tract infections) (within 14 days prior to entolimod administration). Note: Subjects with localized fungal infections of skin or nails are eligible. * Clinical signs of febrile illness (temperature \>99.5oF) * Baseline vital signs with ≥Grade 2 abnormalities * Significant cardiovascular disease (e.g., myocardial infarction, arterial thromboembolism, cerebrovascular thromboembolism, venous thromboembolism) within 6 months prior to study drug administration; symptomatic dysrhythmias or unstable dysrhythmias requiring medical therapy; angina requiring therapy; symptomatic peripheral vascular disease; New York Heart Association Class 3 or 4 congestive heart failure; or uncontrolled Grade ≥3 hypertension (diastolic blood pressure ≥100 mmHg or systolic blood pressure ≥160 mmHg) despite antihypertensive therapy. o Significant screening ECG abnormalities, including unstable cardiac arrhythmia requiring medication, atrial fibrillation, 2nd-degree atrioventricular (AV) block type II, 3rd degree AV block, or Grade ≥2 bradycardia (within 14 days prior to entolimod administration). * Inadequate hepatic function (within 14 days prior to entolimod administration): * Serum alanine aminotransferase (ALT) ≥3 × upper limit of normal (ULN) (Grade ≥1). * Serum aspartate aminotransferase (AST) ≥3 × ULN (Grade ≥1) * Serum alkaline phosphatase (ALP) ≥5 × ULN (Grade ≥2) * Serum bilirubin ≥1.5 × ULN (Grade ≥1) * Positive antiviral serology: * Positive hepatitis C virus (HCV) antibody or positive HCV ribonucleic acid (RNA) by quantitative PCR. * Positive hepatitis B surface antigen (HBsAg) and negative hepatitis B core (HBc) antibody or undetectable hepatitis B (HBV) deoxyribonucleic acid (DNA) by quantitative polymerase chain reaction (PCR) testing. * Positive human immunodeficiency virus (HIV) antibody. * Use of medication that might interact with the flu vaccine including (but not limited to) specifically: aminopyrine, phenytoin sodium, theophylline, and warfarin sodium. * Any ongoing treatment with immunosuppressive or immune-stimulant therapy * Ongoing use of systemic corticosteroids. * Blood or blood products given within the three months prior to vaccination and two months after vaccination * Current and/or expected receipt of chemotherapy, radiation therapy or any other cytotoxic or immunosuppressive therapy \[i.e. more than 10 mg of prednisone given daily or on alternative days for 2 weeks or more in the past 3 months\] * Receipt of another investigational pharmaceutical product within 60 days of treatment * Diagnosis of Parkinson's Disease, previous stroke, or significant cognitive impairment (defined as MMSE \<20) * Other concerns that in the opinion of the PI would preclude a subject from participating in study procedures or from completing the study.