[sarpeedo]

This seems consistent with the fact that Arginine is a conditionally essential amino acid. Our body can naturally make its own Arginine most of the time. When tissues are under increased stress (wound healing is a good example), Arginine becomes essential (the healing tissue can't make enough on its own and needs extra exogenous Arginine).

I'd be curious to see whether this effect is specific to COVID or if Arginine is also beneficial in non-COVID ARDS/Pneumonia.