What about convalescent plasma, an infusion of blood from a COVID-19 survivor that contains antibodies that fight the virus? Not enough is known to recommend for or against it, the guidelines say.
However, enough is known to advise against hydroxychloroquine and certain drugs that affect the immune system -- multiple studies have found them ineffective against the coronavirus.
Aside from drugs, doctors have learned more about ways to treat hospitalized patients, such as putting them on their bellies and other measures that may prevent the need for breathing machines.
