The reason that hydroxychloroquine (HCQ) does not help advanced victims of the virus is the nature of its action. HCQ prevents entry of the virus through the ACE-2 receptor into the cell. Once in the cell, the virus hijacks the cell’s biochemical machinery to replicate more viruses. Several of these replicated viruses erupt through the cell walls, causing great damage, which triggers a reaction that causes major consequences.
So, you have to prevent the virus from getting into the alveoli cells as soon as possible to prevent the replication process and the growth of the viral population. If not stopped soon enough, so much damage is triggered when the immune response really creates havoc.
That’s one of the theories. As I said the treatment for this will likely be multimodal and may be phased. We need those studies everyone reviles so much