This is a Phase 3 study to assess the immune (antibody) response and safety of a Seqirus split virion, inactivated Quadrivalent Influenza Vaccine (Seqirus QIV), in comparison with a US licensed 2016/2017 Quadrivalent Influenza Vaccine (comparator QIV) in a healthy pediatric population 6 months through 59 months of age.