This double-blind (neither researchers nor participants know what treatment participant is receiving) study will evaluate efficacy/safety of pimodivir in combination with SOC treatment versus placebo in combination with SOC treatment in adolescent (13 to 17 years), adult (18 to 65 years), and elderly (greater than [>] 65 but less than or equal to [<=] 85 years) non-hospitalized participants with influenza A infection who are at risk of developing complications. The study will be conducted in 3 phases: screening phase, double-blind treatment period (5 days), a post treatment follow-up period (23 days). Study evaluations include efficacy, clinical and virological outcomes, pharmacokinetics (PK), PK/pharmacodynamics, biomarkers, safety and tolerability. The duration of participation in the study for each participant is 28 days.
The purpose of this study is to evaluate the clinical and virologic benefit of pimodivir in combination with Standard-of-Care (SOC) treatment compared to placebo in combination with SOC treatment.