The purpose of this study is to evaluate the safety and immunogenicity of IL-YANG Inactivated Split Influenza Vaccine (IL-YANG Quadrivalent Seasonal Influenza Vaccine) in healthy infants from 6 months to under 3 years of age(≥ 6 months and < 3 years)

The study is an Randomized, Double-blind, Active controlled Phase III study.

Inclusion Criteria:

1. Healthy infants 'from 6 months to under 3 years of age (≥6 months and <3 years)
2. Born after normal gestation period (which is more than 37 weeks)
3. A subject's legally acceptable representative has voluntarily decided on participation and provided written informed consent after receiving and understanding a detailed explanation on this study

Exclusion Criteria:

1. A history of severe hypersensitivity reactions (e.g., anaphylaxis) to eggs, chicken, and other components of a vaccine including those derived from chicken

2. A history of influenza vaccination within 6 months prior to screening

3. Immuno dysfunction including immunodeficiency diseases or a family history thereof

4. A history of Guillain-Barre syndrome

5. Down's syndrome or cytogenetic disorders

6. Severe chronic diseases (e.g., cardiovascular diseases excluding controlled hypertension, respiratory diseases with respiratory failure, metabolic diseases, renal dysfunction, hemoglobinopathy, etc.) that, in the opinion of investigator, preclude a subject's participation in the study

7. Risk of serious bleeding from an IM injection such as hemophilia patients or those on anticoagulants

8. Acute fever with body temperature exceeding 38.0℃ within 72 hours prior to vaccination with the IP

9. Vaccinated with other vaccines within 28 days prior to screening

10. Received immunosuppressants or immune-modifying drugs within 3 months prior to screening

    ① Azathioprine, cyclosporin, interferon, granulocyte colony-stimulating factor (G-CSF), tacrolimus, everolimus, sirolimus, etc.

    ② Use of high-dose corticosteroids (e.g., continued use of prednisolone at a dose of ≥2 mg/kg/day in subjects weighing <10 kg for 14 days or longer or at a dose of ≥20 mg/day in subjects weighing ≥10 kg for 14 days or longer). However, inhaled, intranasal, or topical corticosteroids are permitted regardless of their dose.

11. Prior use of immunoglobulin or blood products within 3 months prior to screening or their anticipated use during the study

12. Took antipyretics, analgesics, or non-steroidal anti-inflammatory drugs (NSAIDs) within 4 hours prior to vaccination with the IP

13. Participated in another clinical study within 6 months prior to screening

14. Determined ineligible based on other clinically significant medical or psychiatric findings by the investigator