Influenza positive cultures were confirmed using direct immunofluorescence techniques with influenza type-specific antibodies. 3 culture methods were utilized for each NP sample (Classic Flu A and B culture using Madin Darby Canine Kidney cells, Classic Flu A and B culture using Rhesus Monkey Kidney cells, and R Mix Flu A and B culture). The initial molecular test (PCR) was the validated ProFlu+™ assay by Prodesse, Inc., Waukesha, WI, which had been approved by the Food and Drug Administration through a 510K evaluation for specific detection of Influenza A, B or Respiratory Syncytial Virus.

A protocol-defined influenza-like illness was determined by the occurrence of at least 1 of the following respiratory symptoms: sore throat, cough, sputum production, wheezing, or difficulty breathing; concurrently with at least one of the following systemic symptoms: fever (defined as temperature > 99.0°F [> 37.2°C]), chills (shivering), tiredness (fatigue), headache, or myalgia (muscle aches).

Clinical efficacy was assessed in subjects who met all eligibility criteria, received the vaccine they were randomized to, had successful surveillance contact, did not received additional influenza vaccinations and did not have protocol deviations likely to impact their responses for the primary and secondary endpoints (Per-protocol analysis set).

Influenza positive cultures were confirmed by using direct immunofluorescence techniques with influenza type-specific (i.e., for Influenza A and Influenza B) antibodies. For culture confirmation of influenza, 3 different culture methods were utilized for each NP sample (Classic Flu A and B culture using Madin Darby Canine Kidney [MDCK] cells, Classic Flu A and B culture using Rhesus Monkey Kidney [RhMK] cells, and R Mix Flu A and B culture. For antigenic similarity determinations, a standard hemagglutination inhibition test using a panel of ferret antisera (ferret antigenicity testing) was used.

Clinical efficacy was assessed in subjects who met all eligibility criteria, received the vaccine they were randomized to, had successful surveillance contact, did not received additional influenza vaccinations and did not have protocol deviations likely to impact their responses for the primary and secondary endpoints (Per-protocol analysis set).

For culture confirmation of influenza, 3 different culture methods were utilized for each NP sample (Classic Flu A and B culture using Madin Darby Canine Kidney [MDCK] cells, Classic Flu A and B culture using Rhesus Monkey Kidney [RhMK] cells, and R Mix Flu A and B culture).

A protocol-defined influenza-like illness (ILI) was determined by the occurrence of at least one of the following respiratory symptoms: sore throat, cough, sputum production, wheezing, or difficulty breathing; concurrently with at least one of the following systemic symptoms: fever (defined as temperature > 99.0°F [> 37.2°C]), chills (shivering), tiredness (fatigue), headache, or myalgia (muscle aches).

Occurrences of culture-confirmed influenza caused by any influenza viral types/subtypes, in association with a protocol-defined influenza-like illness was assessed in the Per-Protocol Analysis Set.

Influenza positive cultures were confirmed by using direct immunofluorescence techniques with influenza type-specific antibodies. For culture confirmation of influenza, 3 different culture methods were utilized for each NP sample (Classic Flu A and B culture using Madin Darby Canine Kidney cells, Classic Flu A and B culture using Rhesus Monkey Kidney cells, and R Mix Flu A and B culture). For antigenic similarity determinations, a standard hemagglutination inhibition test using a panel of ferret antisera (ferret antigenicity testing) was used.

The modified Centers for Disease Control and Prevention-defined influenza-like illness is the occurrence of fever (defined as temperature > 99.0°F [> 37.2°C]) with cough or sore throat.

Occurrences of culture-confirmed influenza caused by influenza viral types/subtypes that are antigenically similar to those contained in the vaccine formulations, in association with a modified CDC-defined influenza-like illness were assessed in the Per-Protocol Analysis Set.

Influenza positive cultures were confirmed by using direct immunofluorescence techniques with influenza type-specific antibodies. For culture confirmation of influenza, 3 different culture methods were utilized for each NP sample (Classic Flu A and B culture using Madin Darby Canine Kidney cells, Classic Flu A and B culture using Rhesus Monkey Kidney cells, and R Mix Flu A and B culture). For antigenic similarity determinations, a standard hemagglutination inhibition test using a panel of ferret antisera (ferret antigenicity testing) was used.

The modified Centers for Disease Control and Prevention-defined influenza-like illness is the occurrence of fever (defined as temperature > 99.0°F [> 37.2°C]) with cough or sore throat.

Occurrences of culture-confirmed influenza caused by any influenza viral types/subtypes, in association with a modified CDC-defined influenza-like illness were assessed in the Per-Protocol Analysis Set.

Influenza positive cultures were confirmed by using direct immunofluorescence techniques with influenza type-specific antibodies. For culture confirmation of influenza, 3 different culture methods were utilized for each NP sample (Classic Flu A and B culture using Madin Darby Canine Kidney cells, Classic Flu A and B culture using Rhesus Monkey Kidney cells, and R Mix Flu A and B culture). For antigenic similarity determinations, a standard hemagglutination inhibition test using a panel of ferret antisera (ferret antigenicity testing) was used.

Respiratory illness was defined as the occurrence of a new onset (or exacerbation of a pre-existing condition/symptom) of one or more of the following symptoms (that persist for or reoccur after a period of at least 12 hours): sneezing, stuffy or runny nose (nasal congestion), sore throat, cough, sputum production, wheezing, or difficulty breathing.

Occurrences of culture-confirmed influenza caused by influenza viral types/subtypes that are antigenically similar to those contained in the vaccine formulations, in association with a respiratory illness were assessed in the Per-Protocol Analysis Set.

Influenza positive cultures were confirmed by using direct immunofluorescence techniques with influenza type-specific (i.e., for Influenza A and Influenza B) antibodies. For culture confirmation of influenza, 3 different culture methods were utilized for each NP sample (Classic Flu A and B culture using Madin Darby Canine Kidney cells, Classic Flu A and B culture using Rhesus Monkey Kidney cells, and R Mix Flu A and B culture).

Respiratory illness is defined as the occurrence of a new onset (or exacerbation of a pre-existing condition/symptom) of one or more of the following symptoms (that persist for or reoccur after a period of at least 12 hours): sneezing, stuffy or runny nose (nasal congestion), sore throat, cough, sputum production, wheezing, or difficulty breathing.

Occurrences of culture-confirmed influenza caused by any influenza viral types/subtypes, in association with a respiratory illness were assessed in the Per-Protocol Analysis Set.

All serious adverse events, including deaths and adverse events (AEs) of special interest (Guillain Barre Syndrome, Bell's Palsy, encephalitis/myelitis, optic neuritis, Stevens Johnson Syndrome, and toxic epidermal necrolysis) were collected.

Safety was assessed in the Full Analysis Set.