This Study Was Conducted to Evaluate the Safety and Immunogenicity of IVACFLU-S Produced in Children From 6 Months to Under 18 Years Old and the Elderly Over 60 Years Old in Vietnam

Inclusion Criteria: \*Groups from 6 months to under 18 years: * Must have a sponsor (Father / Mother / Legal relative) and get the consent of the sponsor by signing a consent form to participate in the study. (Groups from 6 months to 8 years old must have a direct sponsor, groups 9-17 years old must have an indirect sponsor). * The sponsor must be able to read and write and must commit to taking the child or asking the child to visit on schedule. * If the Sponsor is not the child's parent, he/she must get the consent of the child's father/mother in writing. * Healthy or previous acute illness but stabilized within 2 weeks before injection. * No chronic disease (cancer, heart failure, kidney, liver ...) or chronic disease that has stabilized 3 months before injection. * Children under 1 year old: Must have gestational age ≥ 37 and ≤ 42 weeks at birth and birth weight\> 2500g and not have congenital disease. Children \<60 months of age are not severely malnourished (not exceeding I) Children 6 months to 8 years old who have never received a seasonal flu vaccine (from birth). * Female adolescents who are likely to become pregnant need to be informed of possible risks to the fetus if participating in the study and if participating in the study, must comply with contraceptive measures during the period. research. \*Group over 60 years old * Can read, write (self-report) and ready to sign the consent form to participate in research. * Ability to participate in scheduled visi…