this virus acts like malaria in its blood phase.
Removes iron from red blood cells.
So vitamin C helps in recovery.
People needs oxygen and vitamin C.

Hypoxemia predicts death from severe falciparum malaria among children under 5 years of age in Nigeria: the need for pulse oximetry in case management.
I think covid 19 is some kind of viral malaria.

Iron is removed from the blood by the virus and causes pulmonary edema