Incidence of Laboratory Confirmed Influenza A/B infection was assessed per the study population in the 2008 and 2009 Southern Hemisphere influenza seasons.

Vaccine efficacy = 100 x (1 - ratio of incidence rate). Ratio of incidence rate = active Study Vaccine recipient infection rate / placebo recipient infection rate.

Evaluable Population for the Clinical Endpoint Analysis consisted of all participants who: received study vaccine and clinical endpoint follow-up was longer than 14 days after vaccination; and had not taken any contraindicated medications during the On-study or Clinical Endpoint Periods as potentially impacting clinical endpoint assessments.

Incidence of laboratory confirmed influenza A/B infection due to strains matched to vaccine strains was assessed per the study population in the 2008 and 2009 Southern Hemisphere influenza seasons.

Vaccine efficacy = 100 x (1 - ratio of incidence rate). Ratio of incidence rate = active Study Vaccine recipient infection rate / Placebo recipient infection rate.

Evaluable Population for the Clinical Endpoint Analysis consisted of all participants who: received study vaccine and clinical endpoint follow-up was longer than 14 days after vaccination; and had not taken any contraindicated medications during the On-study or Clinical Endpoint Periods as potentially impacting clinical endpoint assessments.

The criteria for the protocol defined ILI were as follows:

• At least one respiratory symptom:
• cough, sore throat or nasal congestion
• And at least one systemic symptom:
• fever (as defined by oral temperature ≥ 37.8°C (100.0°F), or feverishness (as defined by participant's subjective feeling of fever), chills or body aches.

The CDC ILI case definition was the occurrence of fever (100°F [37.8°C] or higher) in conjunction with either cough or sore throat.

Evaluable Population for the Clinical Endpoint Analysis consisted of all participants who: received study vaccine and clinical endpoint follow-up was longer than 14 days after vaccination; and had not taken any contraindicated medications during the On-study or Clinical Endpoint Periods as potentially impacting clinical endpoint assessments.

Evaluable Population for the Clinical Endpoint Analysis consisted of all participants who: received study vaccine and clinical endpoint follow-up was longer than 14 days after vaccination; and had not taken any contraindicated medications during the On-study or Clinical Endpoint Periods as potentially impacting clinical endpoint assessments.

Evaluable Population for the Clinical Endpoint Analysis consisted of all participants who: received study vaccine and clinical endpoint follow-up was longer than 14 days after vaccination; and had not taken any contraindicated medications during the On-study or Clinical Endpoint Periods as potentially impacting clinical endpoint assessments.

Seroconversion rate: defined as the percentage of participants with either a pre-vaccination HI titer < 1:10 and a post-vaccination HI titer ≥ 1:40 or a pre-vaccination titer ≥ 1:10 and a minimum four-fold rise in post-vaccination HI antibody titer.

Evaluable Population for the Clinical Endpoint Analysis consisted of all participants who: received study vaccine and clinical endpoint follow-up was longer than 14 days after vaccination; and had not taken any contraindicated medications during the On-study or Clinical Endpoint Periods as potentially impacting clinical endpoint assessments.

Seroconversion rate: defined as the percentage of participants with either a pre-vaccination HI titer < 1:10 and a post-vaccination HI titer ≥ 1:40 or a pre-vaccination titer ≥ 1:10 and a minimum four-fold rise in post-vaccination HI antibody titer.

Evaluable Population for the Clinical Endpoint Analysis consisted of all participants who: received study vaccine and clinical endpoint follow-up was longer than 14 days after vaccination; and had not taken any contraindicated medications during the On-study or Clinical Endpoint Periods as potentially impacting clinical endpoint assessments.

Geometric mean fold increase in HI titer was defined as the geometric mean titer (GMT) after vaccination divided by the GMT before vaccination.

Evaluable Population for the Clinical Endpoint Analysis consisted of all participants who: received study vaccine and clinical endpoint follow-up was longer than 14 days after vaccination; and had not taken any contraindicated medications during the On-study or Clinical Endpoint Periods as potentially impacting clinical endpoint assessments.

Geometric mean fold increase in HI titer was defined as the geometric mean titer (GMT) after vaccination divided by the GMT before vaccination.

Evaluable Population for the Clinical Endpoint Analysis consisted of all participants who: received study vaccine and clinical endpoint follow-up was longer than 14 days after vaccination; and had not taken any contraindicated medications during the On-study or Clinical Endpoint Periods as potentially impacting clinical endpoint assessments.

Adverse event grading:

Grade 1 (mild): Symptoms were easily tolerated and did not interfere with daily activities.

Grade 2 (moderate): Discomfort was enough to cause some interference with daily activities.

Grade 3 (severe): Symptoms that prevented normal, everyday activities.

Fever Grade 1: ≥ 37.7°C - < 38.0°C (≥ 99.9 - < 100.4°F) Grade 2: ≥ 38.0°C - < 39.0°C (≥ 100.4 - < 102.2°F) Grade 3: ≥ 39.0°C (> 102.2°F)

Safety Population comprised all participants who received study vaccine (CSL's IVV or placebo) and provided at least one safety assessment after the vaccination.

UAE grading:

Grade 1 (mild): Symptoms were easily tolerated and did not interfere with daily activities.

Grade 2 (moderate): Discomfort was enough to cause some interference with daily activities.

Grade 3 (severe): Symptoms that prevented normal, everyday activities.

Safety Population comprised all participants who received study vaccine (CSL's IVV or placebo) and provided at least one safety assessment after the vaccination.

An SAE was any untoward medical occurrence that at any dose:

• Resulted in death;
• Was life-threatening;
• Required an unexpected in-participant hospitalization or prolongation of existing hospitalization;
• Resulted in persistent or significant disability / incapacity;
• Was a congenital anomaly / birth defect; and / or
• Was medically significant (defined as an event that did not necessarily meet any of the SAE criteria, but was judged by the treating physician to potentially jeopardize the participant or require medical intervention to prevent one of the out

Safety Population comprised all participants who received study vaccine (CSL's IVV or placebo) and provided at least one safety assessment after the vaccination.

An NOCI was defined as the diagnosis of a chronic medical condition where the symptoms commenced or worsened following exposure to study vaccine and may have included those potentially controllable by medication (e.g., glaucoma, hypertension).

Safety Population comprised all participants who received study vaccine (CSL's IVV or placebo) and provided at least one safety assessment after the vaccination.