I wsa diagnosed with Common Variable Immune Deficiency (CVID) after already succumbing to CFS. The treatment for this is IVIG (Intravenous Immunoglobulin). Concomitantly at least, if not causally my CFS symptoms improved considerably. I have been doing IVIIG once a month for about 18 months now. I still do noot know whether there is a causal relationship but I do know I improved from a state of fever, extreme head pain, head ringing, malaise, daily bed rest of 4+ hours to no fever, mild head discomfort, less malaise, much less bedrest, some ability to concentrate and some ability to exercise. I am aware that there is a trajectory of "slow improvement" from extreme beginnings in most cases of CFS and I am by no means well. But I wonder if anyone else has positive tales to tell of using IVIG? Presumably IVIG increases, inter alia, the ability to produce antibodies. Maybe this is effective in helping fight relevant pathogens?