The goal of this study is to determine whether Fluviral, an inactivated, injectable trivalent influenza vaccine (flu shot) is effective in preventing respiratory illnesses that are severe enough to limit normal daily activities and that are shown by virus culture to be caused by influenza viruses. The study will also examine the safety of the vaccine and collect measurements of the immune system responses produced by the vaccine.

Yearly influenza (flu) epidemics cause a large burden of lost work and school time among younger persons and excess hospitalizations and deaths among the elderly. Injectable flu vaccines are generally believed to be effective, but formal studies using modern culture methods to prove this are limited. This study will compare the rate of respiratory illnesses associated with positive influenza virus cultures in healthy younger adults (a group at low risk for serious influenza complications) who have received Fluviral (an injectable flu vaccine) with the rate of such illnesses in healthy younger adults who have received an injection of saline (salt water). The rate of local vaccine reactions and other symptoms will be compared between the vaccine and salt water groups, and the immune responses to the vaccine measured.

Inclusion Criteria:

• Good health by history and physical exam
• Reliable access to a telephone
• Study comprehension and informed consent

Exclusion Criteria:

• Systolic BP >/= 140; diastolic BP >/= 90

• Uncontrolled medical or psychiatric illness (change in last 3 months)

• Cancer, or treatment for cancer within 3 years

• Cardio-pulmonary disease requiring chronic treatment

• Insulin dependent diabetes mellitus

• Renal dysfunction (creatinine >/= 1.7 mg/dL)

• Hemoglobinopathies

• Clotting disorders that increase the risk of IM injections

• Immunosuppressive illnesses or drugs

• History of demyelinating disease (esp. Guillian-Barre syndrome)

• Employment in professions at high risk for influenza transmission

• Household contact with high-risk individuals

• Receipt of:

  a) Immunosuppressive drugs i) systemic glucocorticoids >/= 10 mg prednisone per day ii) cytotoxic drugs b) Investigational drugs within 30 days before, or planned during, the study c) Blood products within 3 months before, or planned during, the study d) Influenza vaccine within 9 months before the study e) Other vaccines within 30 days before, or planned during, the study

• History of:

  1. Severe reactions to other influenza vaccines
  2. Allergy to egg proteins
  3. Sensitivity to mercurials

• Pregnancy/ high risk of pregnancy

  1. Positive urine pregnancy test before treatment
  2. Women of child-bearing potential without credible contraceptive plan