Hemagglutination Inhibition (HI) GMT was assessed at Day 1 and Day 43 for 3 consecutively produced lots.

Per Protocol Set (PPS) - All subjects who received at least one dose of study vaccination and provided at least one evaluable serum sample (lot-to-lot consistency) at relevant timepoints and who correctly received the vaccine, had no major protocol deviations leading to exclusion, and were not excluded due to other reasons.

Percentage of subjects with HI titer ≥ 1:40 at Day 43 was assessed by age cohort (18 to <65 years of age and ≥65 years of age) for the pooled lots. Center for Biologics Evaluation and Research (CBER) criterion for subjects aged 18 to <65 years: The lower bound of the 2-sided 95% CI for the percentage of subjects achieving an HI antibody titer ≥1:40 should meet or exceed 70%. CBER criterion for subjects aged ≥65 years: The lower bound of the 2-sided 95% CI for the percentage of subjects achieving an HI antibody titer ≥1:40 should meet or exceed 60%.

The PPS consisting of all subjects who received at least one dose of study vaccination and provided at least one evaluable serum sample at relevant timepoints who correctly received the vaccine, had no major protocol deviations leading to exclusion, and were not excluded due to other reasons was used for analysis.

Percentages of subjects with solicited local, solicited systemic, and other AEs as measured for 7 days (inclusive) following each vaccination (first and second) and any (first or second) vaccination, by treatment group and calculated for several time intervals after vaccination : 30 minutes, 1 to 3 days (without 30 minutes), 4 to 7 days, and 1 to 7 days (without 30 minutes), and 1 to 3 days (including 30 minutes) and 1 to 7 days (including 30 minutes). Analysis for intervals of the first 30 minutes, days 1 to 3, and days 4 to 7 was not performed.

The overall safety set consisting of all subjects who received a study vaccination who underwent any assessment of local and systemic site reaction and/or assessment of any use of analgesics/antipyretics was used for analysis.

Percentages of subjects with any unsolicited AEs reported through 21 days after each (first and second) and any (first or second) vaccination by treatment group.

The unsolicited safety set consisting of all subjects who received a study vaccination and who underwent any AEs assessment (ie, a subject did not have to have any AEs) was used for analysis.

Percentages of subjects with any adverse events (AE), adverse events of special interest (AESI), new onset of chronic disease (NOCD), and serious adverse event (SAE) through study termination by treatment group.

The unsolicited safety set consisting of all subjects who received a study vaccination and who underwent any AEs assessment (ie, a subject did not have to have any AEs) was used for analysis.

Estimates of hemagglutination inhibition (HI) GMTs, and their associated 95% CIs at Day 1, Day 22, Day 43 and Day 183 were computed using ANCOVA with factors for treatment (active treatment groups or placebo), center and a covariate for the effect defined by the log-transformed prevaccination antibody titer (Day 1).

PPS - All subjects who received at least one dose of study vaccination and provided at least one evaluable serum sample at relevant timepoints and who correctly received the vaccine, had no major protocol deviations leading to exclusion, and were not excluded due to other reasons.

The percentage of subjects with HI titer ≥1:40 data over time by vaccine group and age cohort are presented. CBER criterion for subjects aged 18 to <65 years: The lower bound of the 2-sided 95% CI for the percentage of subjects achieving an HI antibody titer ≥1:40 should meet or exceed 70%.

CBER criterion for subjects aged ≥65 years: The lower bound of the 2-sided 95% CI for the percentage of subjects achieving an HI antibody titer ≥1:40 should meet or exceed 60%.

PPS - All subjects who received at least one dose of study vaccination and provided at least one evaluable serum sample at relevant timepoints and who correctly received the vaccine, had no major protocol deviations leading to exclusion, and were not excluded due to other reasons.

Percentage of subjects achieving seroconversion (defined as: HI titer ≥1:40 for subjects negative at baseline [HI titer <1:10]; or a minimum 4-fold increase in HI titer for subjects positive at baseline [HI titer ≥1:10]) on Day 22, and Day 43 by vaccine group (aH5N1c or placebo) and by age cohort (18 to <65 years of age and ≥65 years of age).

PPS - All subjects who received at least one dose of study vaccination and provided at least one evaluable serum sample at relevant timepoints and who correctly received the vaccine, had no major protocol deviations leading to exclusion, and were not excluded due to other reasons.

Hemagglutination inhibition (HI) GMTs were assessed over time for the vaccine group and age cohort. Adjusted estimates of GMTs, and their associated 95% CIs at Day 1, Day 22, Day 43 and Day 183 were computed using ANCOVA with factors for treatment (active treatment groups or placebo), center and a covariate for the effect defined by the log-transformed prevaccination antibody titer (Day 1).

PPS - All subjects who received at least one dose of study vaccination and provided at least one evaluable serum sample at relevant timepoints and who correctly received the vaccine, had no major protocol deviations leading to exclusion, and were not excluded due to other reasons.

The percentage of subjects with HI titer ≥1:40 data over time by vaccine group and age cohort. Committee for Medicinal Products for Human Use (CHMP) criterion for subjects aged 18 to <60 years: The percentage of subjects achieving an HI titer ≥1:40 is >70%. CHMP criterion for subjects aged ≥60 years: The percentage of subjects achieving an HI titer ≥1:40 is >60%.

PPS - All subjects who received at least one dose of study vaccination and provided at least one evaluable serum sample at relevant timepoints and who correctly received the vaccine, had no major protocol deviations leading to exclusion, and were not excluded due to other reasons.

Percentage of subjects achieving seroconversion (defined as: HI titer ≥1:40 for subjects negative at baseline [HI titer <1:10]; or a minimum 4-fold increase in HI titer for subjects positive at baseline [HI titer ≥1:10]) on Day 22, and Day 43 by vaccine group (aH5N1c or placebo) and by age cohort (18 to <60 years of age and ≥60 years of age)

PPS - All subjects who received at least one dose of study vaccination and provided at least one evaluable serum sample at relevant timepoints and who correctly received the vaccine, had no major protocol deviations leading to exclusion, and were not excluded due to other reasons.

The GMR of HI titers (Day 22/Day 1, Day 43/Day 1) is presented for the vaccine groups and age cohort. CHMP criterion for subjects aged 18 to <60 years: GMR is >2.5. CHMP criterion for subjects aged ≥60 years: GMR is >2.0.

PPS - All subjects who received at least one dose of study vaccination and provided at least one evaluable serum sample at relevant timepoints and who correctly received the vaccine, had no major protocol deviations leading to exclusion, and were not excluded due to other reasons.