The primary efficacy endpoint was the time to alleviation of symptoms calculated as the number of hours from initiation of study drug until the start of the time period in which all 7 symptoms of influenza were either absent or present at a level no greater than mild for at least 21.5 (24 hours - 10%) hours. Subjects with missing diary data were excluded and those who did not experience alleviation of symptoms were censored at the last observed symptom assessment.

The Intent-to-Treat Infected with Influenza A (ITTI-A) population included all subjects who were randomized, received study drug, and had confirmed influenza A by culture or PCR.

Changes from Baseline in log10 TCID50/mL through Days 3, 4, and 9 were presented by treatment group for subjects with positive viral titers at Baseline (log10 TCID50/mL >0.5).

The Intent-to-Treat Infected Influenza A (ITTI-A) population included all subjects who were randomized, received study drug, and had confirmed influenza A infection by culture or PCR.

A subject's severity of illness (area under the symptom score curve, as measured in score-hours) was assessed using available symptom score data until the time of alleviation of symptoms.The score-hours were calculated as the product of the daily symptom score times the hours to alleviation. All available data until time of alleviation were utilized.

The daily symptom score was defined as the sum of the 7 symptoms of influenza recorded by the subject in the diary each day (cough; sore throat; nasal congestion; myalgia [aches and pains]; headache; feverishness; and fatigue), each graded on a 4-point severity scale [0, absent; 1, mild; 2, moderate; 3, severe]); for the composite score, individual scores were summed, with a range from 0 to 21.

The Intent-to-Treat Infected Influenza A (ITTI-A) population included all subjects who were randomized, received study drug, and had confirmed influenza A infection by culture or PCR.

Time to resolution of fever was defined as the number of hours from initiation of study drug until temperature was less than 37.2 °C (99.0 °F) and no antipyretic medication had been taken for at least 12 hours.

The Intent-to-Treat Infected Influenza A (ITTI-A) population included all subjects who were randomized, received study drug, and had confirmed influenza A infection by culture or PCR.

Study personnel were provided with an IRC checklist in the CRF to evaluate the subject for the presence of clinical signs and/or symptoms of the following IRCs: sinusitis, otitis, bronchitis, and pneumonia. Subjects with clinical signs and/or symptoms consistent with these conditions at Screening were not eligible for enrollment in this study.

The Intent-to-Treat Infected Influenza A (ITTI-A) population included all subjects who were randomized, received study drug, and had confirmed influenza A infection by culture or PCR.

Baseline value of influenza virus susceptibility to neuraminidase inhibitors was assessed using virology laboratory tests. Virology laboratory tests included phenotypic characterizations of influenza virus recovered (hemagglutinin and neuraminidase) and viral susceptibility to zanamivir, oseltamivir, and peramivir, as well as genotyping of virus isolates.

A subgroup of the Intent-to-Treat Infected Influenza A (ITTI-A) population that included all subjects who were randomized, received study drug, and had confirmed influenza A (H1N1) infection by culture or PCR. N was 113 for zanamivir susceptibility in the Placebo group.

Change from Baseline to last positive value of influenza virus susceptibility to neuraminidase inhibitors was assessed using virology laboratory tests. Virology laboratory tests included phenotypic characterizations of influenza virus recovered (hemagglutinin and neuraminidase) and viral susceptibility to zanamivir, oseltamivir, and peramivir, as well as genotyping of virus isolates. These analyses were presented separately by treatment group and viral subtype.

A subgroup of the Intent-to-Treat Infected Influenza A (ITTI-A) population that included all subjects who were randomized, received study drug, and had confirmed influenza A (H1N1) infection by culture or PCR. N is for fold change (participants who had baseline and last positive susceptibility values to zanamivir, oseltamivir, and peramivir).

Baseline value of influenza virus susceptibility to neuraminidase inhibitors was assessed using virology laboratory tests. Virology laboratory tests included phenotypic characterizations of influenza virus recovered (hemagglutinin and neuraminidase) and viral susceptibility to zanamivir, oseltamivir, and peramivir, as well as genotyping of virus isolates. Baseline was defined as the last non-missing value occuring prior to the initiation of study drug.

A subgroup of the Intent-to-Treat Infected (ITTI) population that included all subjects who were randomized, received study drug, and had confirmed influenza B infection by culture or PCR. The n reported is the number of participants who had baseline susceptibility values to zanamivir, oseltamivir, and peramivir.

Change from Baseline to last positive value of influenza virus susceptibility to neuraminidase inhibitors was assessed using virology laboratory tests. Virology laboratory tests included phenotypic characterizations of influenza virus recovered (hemagglutinin and neuraminidase) and viral susceptibility to zanamivir, oseltamivir, and peramivir, as well as genotyping of virus isolates. These analyses were presented separately by treatment group and viral subtype. Baseline was defined as the last non-missing value occuring prior to the initiation of study drug.

A subgroup of the Intent-to-Treat Infected (ITTI) population that included all subjects who were randomized, received study drug, and had confirmed influenza B infection by culture or PCR. The n reported is the number for fold change (participants who had baseline and last positive susceptibility values to zanamivir, oseltamivir, and peramivir).