Well, looks like chloroquine may do more harm than good when it comes to a SARS-CoV-2 infection.

We were unable to confirm a benefit of hydroxychloroquine or chloroquine, when used alone or with a macrolide, on in-hospital outcomes for COVID-19. Each of these drug regimens was associated with decreased in-hospital survival and an increased frequency of ventricular arrhythmias when used for treatment of COVID-19.

How bad were the outcomes? About 35% more deaths and more than twice as many serious arrhythmias.

Considering that the patients largely at risk of this disease (mean age in this study: 53.8 years; 30.7% obese; 27.1% smokers) are also often patients in groups typically exhibiting undelying heart conditions, this is very bad news.

Update on 24 May 2020, 18:42 CEST:

Evgeny Kuznetsov has some well argued caveats on this study.