A Study to Evaluate the Immunogenicity and Safety of Seqirus Quadrivalent Influenza Vaccine (QIV) in a Pediatric Population 6 Months Through 59 Months of Age.

The Seqirus study vaccine is a sterile, thimerosal-free suspension containing 60 mcg total hemagglutinin antigen per 0.5 mL (15 mcg each of the four recommended influenza strains for the Northern Hemisphere 2016/2017 influenza season). Subjects will receive one or two doses according to the recommendations of the Advisory Committee on Immunization Practices for the United States 2016-17 Influenza Season. Preferred sites for intramuscular injection are the anterolateral aspect of the thigh in infants 6 months through 11 months of age, the anterolateral aspect of the thigh (or the deltoid muscle of the arm if muscle mass is adequate) in children 12 months through 35 months of age.

The comparator Quadrivalent Inactivated Influenza vaccine is a US-licensed product containing four recommended influenza strains for the Northern Hemisphere 2016/2017 influenza season. Subjects will receive one or two doses according to the recommendations of the Advisory Committee on Immunization Practices for the United States 2016-17 Influenza Season. Preferred sites for intramuscular injection of the non-dominant arm in children 36 months through 59 months of age.