Viral Loads and Duration of Viral Shedding in Adult Patients Hospitalized with Influenza

5.06 � 1.85 3.62 � 2.13 P p .005 +0.03 to +1.68)). Viral RNA concentration demonstrated a nonlinear decrease with time; 26% of oseltamivir- treated and 57% of untreated patients had RNA detected at 1 week after symptom onset. Oseltamivir started on or before symptom day 4 was independently associated with an accelerated decrease in viral RNA concentration (mean b (standard error), 1.19 (0.43) and 0.68 (0.33) log10 copies/mL for patients treated on day 1 and days 2-3, respectively; ) and viral RNA clearance at 1 week (odds ratio, 0.10 (95% confidence interval, 0.03- P ! .05 0.35) and 0.30 (0.10-0.90) for patients treated on day 1-2 and day 3-4, respectively). Conversely, major comor- bidities and systemic corticosteroid use for asthma or chronic obstructive pulmonary disease exacerbations were associated with slower viral clearance. Viral RNA clearance was associated with a shorter hospital stay (7.0 vs 13.5 days; ). P p .001 Conclusion. Patients hospitalized with severe influenza have more active and prolonged viral replication. Weakened host defenses slow viral clearance, whereas antivirals started within the first 4 days of illness enhance viral clearance.