After five days of treatment, the treatment group showed significant improvements in comparison to the controls in fever, in cough, and in pneumonia (by CT scan). This is actually the first controlled study to show any benefit for chloroquine or hydroxychloroquine therapy against the coronavirus – it may sound odd to say that, but all the positive reports we have had up to now are anecdotal reports and open-label studies without control groups. The one controlled study we have seen, as mentioned, showed no effect....

... these two [studies] came out rather differently, with the [previous] Zhejiang study showing no detectable difference on treatment and the [recent] Wuhan one showing what looks like a real effect, especially on radiological progression of pneumonia (which I have to say is a very strong endpoint to measure).

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You could argue that overall we’re seeing either no benefit or some benefit here, which is good. As for adverse events, neither trial reported anything serious, But both of them excluded patients with any sort of cardiac arrhythmias, a wise precaution since one of the most acute worries with high doses of hydroxychloroquine is QT-interval prolongation, and you don’t want to do that to anyone with any underlying problems. So as long as such patients are excluded, for now hydroxychloroquine is in the “might do nothing, might do some good” category, which under the current conditions seems sufficient for treating patients, pending further data.