H5 Booster After a Two Dose Schedule

This study is linked to DMID protocols 04-063, 07-0022 and 08-0059. DMID Study 05-0090 is an extension study to DMID Study 04-063. Between March and May 2005, DMID Study 04-063 enrolled approximately 450 subjects at three study sites. Subjects were stratified by age and history of prior influenza vaccination for the 2004-2005 season, and randomly assigned to receive 2 doses of saline placebo (N=50) or 7.5, 15, 45, or 90 mcg of the influenza A/H5N1 virus vaccine (N=100/dose group) by IM injection. Approximately 6 months after receiving their second vaccination, subjects enrolled in DMID Study 04-063 will return to the clinic for their final study visit (Visit 6). After completing this visit, which includes collection of safety data and a 30-mL blood draw, the unblinded vaccine administrator will determine if the study subject received placebo or the influenza A/H5N1 vaccine. In the proposed extension study (DMID Study 05-0090), subjects who received the influenza A/H5N1 vaccine will be provided with information about DMID Study 05-0090 and asked if they are willing to receive a third dose of vaccine at the same dose level originally administered (i.e., those subjects originally receiving two doses of 7.5 mcg will receive a single booster dose of 7.5 mcg, those receiving two doses of 15 mcg will receive a single booster of 15 mcg, etc.). Subjects that provide informed consent and are eligible for DMID Study 05-0090 will be given a third dose of the vaccine at the same dose level they previously received by the unblinded vaccine administrator. Symptoms and signs will be assessed in the clinic for 15 to 30 minutes after inoculation, and the subjects will maintain a memory aid to record oral temperature and systemic and local adverse events (AEs) for 7 days after each immunization. Subjects will be encouraged to take their temperature around the same time each day. All subjects will receive a safety follow-up telephone call at 1 to 3 days to elicit any AE information and between 13 to 19 days after the vaccination to elicit any AE information and review the memory aid. Subjects will return to the clinic 28 (+/- 3) days after vaccination for assessment of AEs and concomitant medications, targeted physical examination (if indicated) and blood sample collection. During this follow-up visit, subjects who have been identified as "high responders" to the vaccine in the DMID 04-063 study will also be solicited to participate in a blood specimen collection substudy. Subjects will be provided with information about the substudy and asked if they would consent to have an additional 100 mL of blood drawn after the blood sample is collected for serum antibody assays. Refusal to consent for this substudy does not preclude subjects from continuing in the booster vaccine trial. At approximately Day 180 (6 months after booster vaccination), subjects will return to the clinic for a final immunogenicity blood sample collection and for follow-up, which may include a targeted physical examination (if indicated). The duration of the study treatment for each subject in this study will be about 6 months.