Totally anecdotal, because clinical studies aren't being done with placebos, but I talked with my doctor about COVID-19 a couple of weeks ago, and he said the standard treatment by every doctor in the county affiliated with the hospital (which is all of them) has been Hydroxychloroquine with a Z-pack and zinc. If someone tests positive for COVID-9, but has no symptoms, they are tested again in 3-5 days. If they test positive a second time, they are immediately put on the medications. If they have symptoms and test positive, they are put on the medications. He's had one patient and knows of two others who did not receive hydroxychloroquine because they have the standard pre-existing risk factors that put them at high risk of heart attacks and other issues with the drug. Those people would never be prescribed the drug for any reason. He said about a dozen patients who tested positive were already taking the drug because of rheumatoid arthritis and they never showed any symptoms.
At the time this was out of 75 or 77 confirmed positive tests (it's now 89 in the county, 74 cases fully recovered, 12 isolated at home, 2 hospitalized, and 1 death), and the first 6 patients who came down with it were not given the medications. Of those 6, one died, and would not have been a candidate for HCQ in the first place (heart transplant recipient, one year, and was already on supplemental oxygen). He was 88 years old.
Again, anecdotal, not a clinical study, but that's a pretty strong argument in favor of that particular medical treatment.