“A great many cases of ME follow viral infection and/or vaccination. In these conditions the immune system is switched on to fight the offending microbe. In the short term this is highly desirable. To be effective, all vaccinations contain immune adjuvants which are there specifically to fire up the immune system. When this works in our favour, we call it immunity. However, when it works against us, we call it allergy. Clinically, we know that vaccinations can trigger allergies. There is no doubt that there are some ME patients who do not recover until they start taking antivirals (see work by Dr Martin Lerner in : Valacyclovir in the treatment of post viral fatigue syndrome ) In these cases, there is often no overt evidence of infection. I suspect what is going on here is that these microbes are present in low levels which would not normally cause harm to the body, but the immune system continues to fight. It is a sort of inappropriate immune activation against microbes or “allergy” to microbes. This is hugely wasteful of energy. Such patients will have a large immunological hole draining their daily energy bucket. See Energy Expenditure in ME/CFS: Immune wastage of energy and Rituximab” Dr. Sarah Myhill, from her book – Diagnosing and Treating Chronic Fatigue Syndrome