According to this report, absolute humidity affects transmission and survival of the influenza virus with 90% accuracy. Lower humidity at winter promotes both the influenza virus transmission and its survival.
Is there any evidence that increasing humidity levels positively affects the prognosis of someone who's already been infected with the virus (i.e, either shortens the duration or diminishes the severity of the illness, not including obvious symptoms such as easing congestion etc)?
The only reason to believe this might be true is that higher humidity levels might also increase moisture in the nasal cavity thus weakening the virus but this is just a theory.
Does anyone have concrete data on this subject?