I've always imagined that 'my' POIS was of an auto-immune nature, so Dr. Waldinger's announcement wasn't of much surprise to me. Of course, it actually delighted me, because I felt I saw a real potential for an end to my problem.
We each have a gut feel inside, as to the origin of this thing. My POIS tends to be more physical, and some parts of it are no doubt allergy type reactions, like itchy eyes, congestion, stuffed nose etc. Other parts of it less so, like sore joints and jsut feeling sick.
It's a little harder to relate the brain fog and mood changes to allergies, although I feel that Dr. Waldinger had gone a fair ways for me in making the relationship.
But, each of us has a slightly different POIS and in some it has much stronger mental symptoms. The gut feel is different there. And in many, it's still hard to accept the auto-immune theory.
For those we have a complete category, where they can explore this other potential line of POIS.