There is not, as of writing, any medication which has been shown in controlled trials to significantly hasten recovery from covid-19, the disease caused by the coronavirus that's become a global pandemic. Last week, there were nonetheless some new developments on that front. One drug seems to show signs of promise. Another has seen red flags raised. The one that's raised hopes isn't the one that President Donald Trump has been hyping. Again: It is not the case that we have new, incontrovertible proof of a drug's efficacy. But news of a trial demonstrating some benefit for covid-19 patients from...