[hannob]

> In this case (as with many others) placebo is pretty effective

Where do you get that idea from? In the study it looks like everyone got better, but that may just be regression to the mean (i.e. the normal progression of covid-19 in those patients).

If you'd want to know if placebo is effective on covid-19 you'd have to do a completely different study, comparing placebo to doing nothing. Though the likelyhood that placebo therapy is "pretty effective" here is very low. Placebos usually work best in things that have a strong subjective factor, e.g. pain treatment.