Immunogenicity and Safety of Butantan Quadrivalent Influenza Vaccine (Split Virion, Inactivated) in Infants and Children .

Inclusion Criteria:

1. Healthy infant and child of either sex aged between 6 and 35 months on the day ofthe first study vaccination.

2. Born at term (≥ 37 weeks of gestational age) and birth weight ≥ 2.5 kg.

3. Parents/legal guardians of the infant or child able and willing to attend allscheduled visits and comply with all study procedures, including blood draws.

4. Parents/legal guardians of the infant or child have provided informed consent.

Exclusion Criteria:

1. Having received any influenza vaccine from the current season and/or 6 months beforethe first study vaccination.

2. History of allergy to egg, chicken proteins, or other components of the influenzavaccine.

3. History of serious adverse reaction to any influenza vaccine.

4. Have any clinically significant condition or situation that, in the Investigator'sopinion, would interfere with study evaluations or participation.

5. History of Guillain-Barré or other demyelinating diseases.

6. History of neurological disease and/or clinically significant developmental delay (at the discretion of the Investigator), or seizure (except for an isolated febrileseizure episode).

7. Having received immune globulin, blood, or any blood product 3 months before theplanned date of the first study vaccination or planned administration during thestudy period.

8. Any confirmed or suspected immunosuppressive condition, congenital or acquiredimmunodeficiency (including human immunodeficiency virus - HIV) based on medicalhistory and physical examination.

9. Immediate personal or family history of congenital immunodeficiency.

10. Having received or are using radiation therapy, chemotherapy, immunosuppressivedrugs, or other immunomodulatory drugs within three months before the planned dateof the first study vaccination or planned use during the study.

11. Be a solid organ or bone marrow/stem cell transplant recipient.

12. Thrombocytopenia, bleeding disorder, use of anticoagulants, or any condition thatcontraindicates intramuscular injection.

13. Significant chronic disease (cancer, autoimmune disease, diabetes mellitus, acute orprogressive liver disease, acute or progressive kidney disease, severe heart or lungdisease) or which in the Investigator's opinion poses a risk to the health of theinfant or child participating in the study or which may interfere with the conductor conclusion of the study.

14. History of seropositivity for human immunodeficiency virus (HIV), hepatitis B, orhepatitis C.

15. Major surgery or surgery using general anesthesia planned to occur during the periodbetween the first vaccination and 28 days after full vaccination in the study.

16. Any condition that, in the opinion of the Investigator, may interfere with theconduct or completion of the study (such as travelling or planned moving ofresidence, among others).

17. Participation in another clinical trial involving another experimental orunregistered product 1 year before the planned date of the study's firstvaccination, or plans to entering a clinical trial during the study.

18. Infant and institutionalized child.

19. Be related to the Investigator, research site staff member, or employee directlyinvolved in the study.

Postponement Criteria:

1. Have received any vaccine (including routine childhood vaccines) within 28 days ofthe first study vaccination (delay until the 28-day deadline from the date of thelast vaccination).

2. Moderate or severe (as judged by the Investigator) acute illness/infection orfebrile illness (temperature ≥ 37.8°C) 48 hours before the planned date of the firststudy vaccination.

3. Acute respiratory illness within 14 days preceding the planned date of the firststudy vaccination.