It is quite possible that there is a simple reason why those on...

It is quite possible that there is a simple reason why those on placebo have a significant beneficial effect.
One of the major triggers for viral shedding is stress and anxiety .... and when you find you have this curse your personal stress levels go through the roof as you realise the disaster that has hit you.
So here you are in the trial, but you are in the inner sanctum where the whispers would tell you that this is it .... this is the cure ... and after the trial you will get access to "the good stuff" ... what a relief!
Anxiety must drop .... thus viral shedding drops ....