This is a Phase II randomized, partially-blinded, controlled trial in males and females, 65 years of age and older, who are in good health and meet all eligibility criteria. This clinical trial is designed to assess the safety, reactogenicity, and immunogenicity of a monovalent inactivated influenza A/H7N9 virus vaccine, derived from the influenza A/Shanghai/2/2013 virus, manufactured by Sanofi Pasteur administered intramuscularly at different intervals and dosages (3.75, 7.5, or 15 mcg of HA/0.5 mL dose) given with MF59 adjuvant manufactured by Novartis Vaccines and Diagnostics. Subjects will be assigned randomly to 1 of 6 groups (60 to 100 subjects per group) to receive three doses intramuscularly of the inactivated A/H7N9 vaccine at dosages (3.75, 7.5, or 15 mcg of HA/0.5 mL dose) given with MF59 adjuvant using two different study vaccination schedules. The first and third study vaccinations will be administered to all subjects on Day 1 and approximately Day 169. The second study vaccination will be administered either on approximately Day 29 for Groups 1, 3, and 5 or approximately Day 57 for Groups 2, 4, and 6. Reactogenicity will be measured from the time of each study vaccination through 8 days after each study vaccination by the occurrence of solicited injection site and systemic reactions. Unsolicited non-serious adverse events (AEs) will be collected from the time of each study vaccination through approximately 28 days after each study vaccination. Serious adverse events (SAEs) and new-onset chronic medical conditions will be collected from the time of the first study vaccination through approximately 12 months after the last study vaccination.

Immunogenicity testing will include performing hemagglutination inhibition (HAI) and neutralizing (Neut) antibody assays on serum obtained immediately prior to the first study vaccination (Day 1), approximately 28 days after the second study vaccination (approximately Day 57 for Groups 1, 3, and 5; approximately Day 85 for Groups 2, 4, and 6), immediately prior to the third study vaccination (approximately Day 169), and approximately 28 days after the third study vaccination (approximately Day 197). Subjects in Groups 1, 3, and 5 will also have immunogenicity testing for HAI and Neut antibody assays performed on serum obtained at approximately 56 days after the second study vaccination (approximately Day 85). Between 360 and 600 subjects will be enrolled in this trial. Study Duration is approximately 30 months and Subject Participation is approximately 18 months. The primary objectives are to (1) assess the safety and reactogenicity of different dosages (3.75, 7.5, and 15 mcg of HA/0.5 mL dose) of an MF59-adjuvanted, monovalent inactivated influenza A/H7N9 virus vaccine using two different study vaccination schedules and (2) assess the serum hemagglutination inhibition (HAI) antibody responses to different dosages (3.75, 7.5, and 15 mcg of HA/0.5 mL dose) of an MF59-adjuvanted, monovalent inactivated influenza A/H7N9 virus vaccine using two different study vaccination schedules following receipt of the second study vaccination. The secondary obectives are to (1) assess study vaccine-related unsolicited non-serious adverse events following receipt of different dosages (3.75, 7.5, and 15 mcg of HA/0.5 mL dose) of an MF59-adjuvanted, monovalent inactivated influenza A/H7N9 virus vaccine using two different study vaccination schedules, (2) assess new-onset chronic medical conditions following receipt of different dosages (3.75, 7.5, and 15 mcg of HA/0.5 mL dose) of an MF59-adjuvanted, monovalent inactivated influenza A/H7N9 virus vaccine using two different study vaccination sched