Where can i find references indicating whether or not hydroxychloroquine is effect/not effective against covid-19?

A very reliable source, the Cochrane review, reported the following: Hydroxychloroquine does not reduce deaths from COVID-19, and probably does not reduce the number of people needing mechanical ventilation. It caused more unwanted effects than a placebo treatment. The authors did not think any new studies of hydroxychloroquine should be started for treatment of COVID-19.

Originally, it was anecdotal case reports that suggested value of hydroxychloroquine in early infections. But no consistent study supports value if infection worsens. At this point, cannot recommend this medication, but might Google Dr Zalenko’s work in area