Inclusion Criteria:

• Men and women of age 65 years and older at the time of enrollment.
• Eligible to receive Fluzone.
• 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 Criteria:

Study candidates who meet any of the following criteria within 28 days prior to entolimod administration will not be eligible for participation in this study:

• Receipt of any other vaccines within the past 30 days prior to enrollment.
• Acute illness within the last 30 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 >99.5°F).
• Baseline vital signs with ³ 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.
• 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) ³3 × upper limit of normal (ULN) (Grade ³1);
  • Serum aspartate aminotransferase (AST) ³3 × ULN (Grade ³1);
  • Serum alkaline phosphatase (ALP) ³5 × ULN (Grade ³2);
  • Serum bilirubin ³1.5 × ULN (Grade ³ 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.