Immunogenicity, Safety and Tolerability of CSL Limited Inactivated Influenza Vaccine in Adults

The purpose of this Phase III, randomized, double-blinded, placebo-controlled, multi-center study is to evaluate the immunogenicity, safety, and tolerability of CSL Limited Inactivated Influenza Vaccine in adults ages 18 to less than 65. The primary objective of this study is to demonstrate that vaccination with CSL Limited Inactivated Influenza Vaccine produces an immune response sufficient to meet the Committee for Medicinal Products for Human Use (CHMP) criteria for young adults of 40% serorconversion and 70% seroprotection. Secondary objectives are to: demonstrate clinical consistency between 3 lots (batches) of CSL Limited Inactivated Influenza Vaccine multi-dose vial presentation (Thimerosal containing); to demonstrate clinical consistency between CSL Limited Inactivated Influenza Vaccine multi-dose vial presentation (Thimerosal containing) and CSL Limited Inactivated Influenza Vaccine pre-filled syringe presentation (Thimerosal-free); and to demonstrate acceptable safety and tolerability of CSL Limited Inactivated Influenza Vaccine multi-dose vial presentation (Thimerosal containing) and pre-filled syringe presentation (Thimerosal-free). Primary endpoints are seroprotection rate and seroconversion rate. Seroprotection is defined as a minimum post-vaccination humagglutination inhibition (HI) titer of 1:40, and seroconversion is defined as an increase in HI antibody titer of at least 4-fold, with a minimum post-vaccination HI titer of 1:40. Secondary endpoints are: comparison of the Geometric Mean Titers to influenza hemagglutinin antigens post vaccination of the active treatment arms; and the number and rate of the type, frequency and intensity of adverse events (AE) in the active treatment arms. Approximately 1250 (and up to 1359) healthy adults, ages 18 to less than 65 years old, will be enrolled into this clinical trial. Subjects who meet the inclusion criteria for the study will be randomized in a 1:1:1:1:1 ratio to receive 1 of 3 lots of vaccine in multidose vials, a single lot of vaccine in pre-filled syringes or placebo in multi-dose vials (250 subjects per group). Vaccine will be prepared and administered by an unblinded vaccine administrator, who will not be involved in subsequent assessments. Subjects will be observed in the clinic for at least 30 minutes after vaccination, and subjects will maintain a 5-day, post-vaccination solicited AE and local reaction memory aid and a 21-day unsolicited AE memory aid. Subjects will return to the clinic at day 5 to review their reactogenicity memory aid. Subjects will also return to clinic on Day-21 post-vaccination for AE and concomitant medication assessment, a targeted physical examination (if indicated), and a review of the memory aid. Serum for antibody titers will be drawn prior to vaccination and on Day-21 post-vaccination. Subjects will participate for up to 24 days.