Here’s what an infectious disease doctor tied to a major nyc hospital told me about this study:

“This is probably the worst of study designs: retrospective analysis, with no stated methods as to how patients were assigned one of three treatment arms.” https://www.politico.com/news/2020/04/21/malaria-drug-virginia-coronavirus-study-198590

In addition, the three groups were not entirely comparable, and all were sick enough to be hospitalized. 

A key indicator of prognosis, fibrin degradation products, was not even measured.

“It may be proven true in subsequent, prospective trials, we should understand proponents of the use of hydroxychloroquine in various combinations with other drugs all suggest that the drug is most effective when used early, well before patients "qualify" for hospitalization.”

“This is similar to the way we use oseltamivir or baloxavir for influenza: unless started within 72 hours of onset of viral symptoms, these effective, proven, and licensed drugs have little or no demonstrable effect on the course of influenza.”

“However, we still routinely will use them in advanced, late (>72 hours) influenza patients who are sick enough to be admitted to he hospital”

So basically, this study does not refute previous positive studies, and more clinical trials are necessary-

We can still be hopeful