Is there a methodological concern about how the uninfected "controls" are established? (I have not read the papers you linked) It seems like: (a) Obviously th

Is there a methodological concern about how the uninfected "controls" are established? (I have not read the papers you linked) It seems like: (a) Obviously they're not intentionally infecting one group and keeping the other in rigid isolation so ... (b) it seems like it would be hard to rule out that there's something else that's characteristic of people who avoided infection which could be related? To be clear, I'm not trying to throw skepticism at the conclusion that infection causes deficits -- but isn't it kinda hard to measure? In the same way that, e.g. it's hard to measure the very long-term effects of forever chemicals or microplastics or other things that are so inescapably pervasive.