I haven't used immunovir, but I trialed inosine a few years ago, which I think should be quite similar in effect. Back then I reacted badly to it like with any immune stimulant; basically increase of brain fog, anxiety, fatigue, neuropathic pain, etc. The amplitude of all symptoms increased, nothing like as with the flu/cold, so I couldn't tolerate taking these supplements for over a week.
It could be that I would react differently now, as I read CFS/ME patients after three years with this disease develop a different cytokine profile, so it's possible I would tolerate it better now. The only immune modulator that I've been able to take and still use is LDN.