Subjects used the FLU-PRO questionnaire once daily in the evening to score the severity of 32 FLU-PRO symptoms. Symptom response was deemed achieved when the rating for each of the 32 FLU-PRO symptoms was ≤ its assigned threshold for 2 consecutive daily diary periods without use of symptom relief medication. The symptom response thresholds were developed by applying an algorithm to blinded symptoms data to select the set of 32 symptom thresholds most closely associated with patient-reported usual health.

The ITTI (primary efficacy) population consisted of all subjects positive for influenza by RT-PCR at Baseline.

Subjects completed a diary including rating ability to perform normal activities on a scale from 0 (able to perform no normal activities) to 10 (able to perform all normal activities) daily in the evening. The time from first dose to ability to perform all normal activities is the time in hours between the first dose of study medication and that time when the subject first reported a score of "10" (able to perform all normal activities) for two consecutive daily diary periods without use of symptom relief medication.

The ITTI (primary efficacy) population consisted of all subjects positive for influenza by RT-PCR at Baseline.

Complications of influenza infection included pneumonia, otitis media, bronchitis, sinusitis, worsening of pre-existing health conditions, systemic antibiotic use for infections secondary to influenza infection, hospitalization due to influenza or complications of influenza and death.

The ITTI (primary efficacy) population consisted of all subjects positive for influenza by RT-PCR at Baseline

Subjects used the FLU-PRO questionnaire once daily in the evening to score the severity of 32 FLU-PRO symptoms. Symptom response was deemed achieved when the rating for each of the 25 FLU-PRO symptoms (excluding gastrointestinal and eye symptoms) was ≤ its assigned threshold for 2 consecutive daily diary periods without use of symptom relief medication. The symptom response thresholds were developed by applying an algorithm to blinded symptoms data to select the set of 25 symptom thresholds most closely associated with patient-reported usual health.

The ITTI (primary efficacy) population consisted of all subjects positive for influenza by RT-PCR at Baseline

Subjects completed the FLU-PRO questionnaire including global assessment questions daily in the evening. The time from first dose to ability to return to usual health is the time in hours from the first dose of study medication to the first time when the subject answered "Have you returned to your usual health?" with "yes" for two consecutive daily diary periods without the use of symptom relief medication.

The ITTI (primary efficacy) population consisted of all subjects positive for influenza by RT-PCR at Baseline.

The proportion of patient diaries misclassified by the response definition used for the primary efficacy analysis compared to patient reported usual health. A diary was considered "misclassified" if the response definition predicted "responded" and the patient reported not being at usual health or if the response definition predicted "not responded" and the patient reported being at usual health.

The ITTI (primary efficacy) population consisted of all subjects positive for influenza by RT-PCR at Baseline. Per the Statistical Analysis Plan, the response definition misclassification rate was to be calculated prior to unblinding including all data for subjects in the ITTI population.

The correlation coefficient between sustained response and return to usual health was calculated for the pooled ITTI population (i.e., not by treatment group) as a measure of association between the primary endpoint response definition and its intended anchor, patient-reported return to usual health.

The correlation coefficient between sustained response and return to usual health was to be calculated prior to unblinding including all data for subjects in the ITTI population, consistent with the misclassification rate as specified in the statistical analysis plan.

Survival analysis of Time to Return to Usual Health was repeated for subjects with laboratory-confirmed influenza (ITTI population) who were randomized to the placebo treatment group by whether the subjects had detectable anti-influenza antibodies at Baseline.

Subjects with laboratory-confirmed influenza (ITTI population) who were randomized to the placebo treatment group by whether the subjects had detectable anti-influenza antibodies at Baseline.

Alternative means of endpoint construction were pursued to strengthen the relationship between symptoms-based endpoint measures and subject global assessments of health. Time to Sustained Clinical Recovery is an endpoint based on evidence of meaningful within-subject change sustained for the duration of the study. Time to Sustained Clinical Recovery is the time in hours from the first dose of study medication to the first time at which the subject reports a decrease in total FLU-PRO score from the previous diary with assessment that symptoms are at least "somewhat better than yesterday", no oral temperature ≥100.4 F in the prior 24 hours, and no future increase in any of the FLU-PRO domains except within validated background levels.

The ITTI (primary efficacy) population consisted of all subjects positive for influenza by RT-PCR at Baseline.

Alternative means of endpoint construction were pursued to strengthen the relationship between symptoms-based endpoint measures and subject global assessments of health. Time to Sustained Clinical Recovery is an endpoint based on evidence of meaningful within-subject change sustained for the duration of the study. Time to Sustained Clinical Recovery is the time in hours from the first dose of study medication to the first time at which the subject reports a decrease in total FLU-PRO score from the previous diary with assessment that symptoms are at least "somewhat better than yesterday", no oral temperature ≥100.4 F in the prior 24 hours, and no future increase in any of the FLU-PRO domains except within validated background levels.

Placebo-treated subjects with and without anti-influenza antibodies detected at Baseline who were positive for influenza by RT-PCR.

Alternative means of endpoint construction were pursued to strengthen the relationship between symptoms-based endpoint measures and subject global assessments of health. Time to Sustained Clinical Recovery is an endpoint based on evidence of meaningful within-subject change sustained for the duration of the study. Time to Sustained Clinical Recovery is the time in hours from the first dose of study medication to the first time at which the subject reports a decrease in total FLU-PRO score from the previous diary with assessment that symptoms are at least "somewhat better than yesterday", no oral temperature ≥100.4 F in the prior 24 hours, and no future increase in any of the FLU-PRO domains except within validated background levels.

Subjects positive for influenza by RT-PCR at Baseline with anti-influenza antibodies detected in a Baseline serum sample.

Alternative means of endpoint construction were pursued to strengthen the relationship between symptoms-based endpoint measures and subject global assessments of health. Time to Sustained Clinical Recovery is an endpoint based on evidence of meaningful within-subject change sustained for the duration of the study. Time to Sustained Clinical Recovery is the time in hours from the first dose of study medication to the first time at which the subject reports a decrease in total FLU-PRO score from the previous diary with assessment that symptoms are at least "somewhat better than yesterday", no oral temperature ≥100.4 F in the prior 24 hours, and no future increase in any of the FLU-PRO domains except within validated background levels.

Modified ITTI population consists of subjects with laboratory-confirmed influenza infection without detectable anti-influenza antibodies at Baseline and Baseline subject-reported assessment that symptoms are present, the symptoms are not consistent with the subject's usual health, the symptoms interfere with daily activities, and the symptoms have worsened or remained the same relative to the previous day. Assessment was completed via the Baseline FLU-PRO questionnaire.