This trial is designed as a blinded, randomized and parallel group study to investigate the clinically recommended dosage for ASP7374 based on the comparison of the immunogenicity and safety among two doses of subcutaneous ASP7374 and one dose of intramuscular ASP7374 in healthy adults.

Inclusion Criteria:

• Body weight: Female: ≥40.0 kg, <70.0 kg, Male: ≥50.0 kg, <80.0 kg
• BMI: ≥17.6, <26.4
• Healthy, as judged by the investigator or sub-investigator based on the results of physical examinations (subjective symptoms and objective findings) and all tests obtained

Exclusion Criteria:

• Scheduled to receive another vaccine during study participation period
• Received influenza vaccine within 180 days prior to the study
• Received or scheduled to receive a live vaccine within 28 days prior to vaccination of the study vaccine, and received or scheduled to receive an inactivated vaccine or a toxoid within 7 days prior to vaccination of the study vaccine
• Diagnosis of immune deficit in the past, has a family member (within the third degree of kinship) with a diagnosis of congenital immunodeficiency syndrome
• Past history of anaphylactic shock or an allergic reaction such as generalized eruption due to food or drug (including vaccines) allergies, fever ≥ 39.0°C within 2 days after the previous vaccination (influenza vaccine and others)
• Female subjects who are breastfeeding, pregnant, possibly pregnant, and planning to become pregnant during the study period