I'm not a doctor, I'm not embassy staff, and I'm not a Russian agent, so my opinion doesn't matter, but this one has smelled to me like "Chronic Lyme Disease but for spooks" since it came out. the combination of symptoms that doctors can't figure out, the belief in a coverup, pinning it on secret russian weaponry - the whole thing is a tall claim with short proof.

the simpler answer is that like chronic lyme, it's a collection of psychosomatic symptoms and random other ailments that get unified and blamed with this label. that doesn't make the symptoms not real, and it's got no more weight behind it than the spy weapon theory, but you can't prove a negative except by showing what isn't true. none of the studies so far have found anything.

my views on this are colored by my biases, but without getting into any of the political side of it, i think that looking at the medical evidence and the announcements made by the US govt etc on this is enough to warrant caution at a minimum when things like this come out