-The subject must have previously received at least 2 doses via the intramuscular route of placebo or vaccine derived from A/H5N1/VN/1203/04 as part of one of the following DMID Protocol Nos.: 04-062, 04-063 (and 05-0090), 04-076, 05-0015, 05-0127, 05-0141, or 06-0089; or the subject must have received placebo intramuscularly as part of DMID Protocol No. 06-0052. -The subject must be 19 years old or older. -Women of childbearing potential (not surgically sterile via tubal ligation, bilateral oophorectomy or hysterectomy or who are not postmenopausal for greater than or equal to 1 year) must agree to practice adequate contraception, including, but not limited to, abstinence, monogamous relationship with vasectomized partner, barrier methods such as condoms, diaphragms, spermicides, birth control pills, patches or hormonal shots or hormonal implants, NuvaRing and IUDs (intrauterine devices), during the study period between enrollment and 30 days following receipt of the last dose of vaccine. -For a female subject of childbearing potential, she must have a negative pregnancy test (urine or serum) within 24 hours prior to vaccination. -The subject is in good health, as determined by vital signs (heart rate less than 100 bpm; blood pressure: systolic greater than or equal to 90 mm Hg and less than or equal to 140 mm Hg; diastolic less than or equal to 90 mm Hg; oral temperature less than 100.0 degrees Fahrenheit), medical history to ensure stable medical condition, and a targeted physical examination, when necessary, based on medical history. A systolic blood pressure of less than or equal to 160 and a diastolic blood pressure of less than or equal to 90 is acceptable in subjects greater than 65 years of age. -The subject is able to understand and comply with the planned study procedures, including being available for all study visits. -The subject has provided informed consent prior to any study procedures.