Here is a response re. plasma from TFT. Sounds very encouraging.
A close friend of mine worked in the Covid unit of a local hospital from the beginning of the pandemic. She told me a couple of months ago that convalescent plasma stops it in its tracks. She said that HCQ is good (they used it until the plasma became available) but plasma is better. by pax_et_bonum on TFT
Did your friend say anything about IVIG? Was it tried and useful?