CFS can sometimes be a bit more complictated than just the viral load. But the viral load can play a big part.
Adrenal fatigue is often the cause of a low immune sytem. Although this is not always the case. That is why I would suggest if someone is not sure if they have AF to check their temperatures.
Being in a low metabolic state will often compromise the immune system by allowing in viruses. This in turn lets in heavy metals, bacteria, funguses ect. Viruses and heavy metals love to live together :) Its a vicious circle. This in turn makes the adrenals weaker and more difficult to heal no matter how many supplements you throw at it.
In the end you land up in a position where you can't detox the heavy metals because your adrenals are too weak. The supplemsenst are not working because of the viruses, heavy metals, funguses. A right mess :)
Dr Amy Yasko who does a lot of work with Autistic children picked this up ages ago.( The viruses and heavy metals)