@lenora - the article mentions a company called Axcella which has come up with a proprietary blend of cheap amino acids to treat Long Covid. From
their website, the blend includes: branched chain amino acids (leucine, isoleucine, valine), arginine, n-acetyl-cysteine, carnitine, serine and glutamine. I already take all of those except for serine and arginine. I did try arginine once with mixed results and then tried citrulline - supposed to be a vasodilator but it raised my BP quite high instead! So stopped it.
It bothers me a bit that they're going to come up with a no doubt very expensive "drug" which will cost pennies to make. These are all readily available to all of us. I've written about the benefits of BCAAs many times and they have helped many here, though have not got at the root cause of ME/CFS (if there is a root cause, which I think there must be). I've never tried serine - maybe will add it to my list.