Hydroxychloroquine has not been shown to be effective in any large and well designed clinical trial. A large number of studies have shown no benefit to hydroxychloroquine for COVID-19 patients.
There was initial excitement when positive results were shown very early in the pandemic, when an open-label non-randomized trial (https://www.sciencedirect.com/science/article/pii/S0924857920300996?via%3Dihub) including only 36 hospitalized patients purported to show “a rapid and effective speeding up of their healing process, and a sharp decrease in the amount of time they remained contagious.”
From there, the treatment became highly politicised, as it was endorsed by President Trump despite no health official in the United States endorsing the drug.
In June 2020, the FDA revoked the emergency use authorization (EUA) of oral hydroxychloroquine and chloroquine phosphate for the treatment of COVID-19.
"Among adults hospitalized with respiratory illness from COVID-19, treatment with hydroxychloroquine, compared with placebo, did not significantly improve clinical status at day 14. These findings do not support the use of hydroxychloroquine for treatment of COVID-19 among hospitalized adults."
RCT w/491 patients: "Hydroxychloroquine did not substantially reduce symptom severity in outpatients with early, mild COVID-19."
RCT w/4716 patients: "Patients in the hydroxychloroquine group had a longer duration of hospitalization than those in the usual-care group and a lower probability of discharge alive within 28 days"
RCT w/667 patients: "Among patients hospitalized with mild-to-moderate Covid-19, the use of hydroxychloroquine, alone or with azithromycin, did not improve clinical status at 15 days as compared with standard care."
RCT w/4674 patients: "We have concluded that there is no beneficial effect of hydroxychloroquine in patients hospitalised with COVID-19. We have therefore decided to stop enrolling participants to the hydroxychloroquine arm of the RECOVERY trial with immediate effect."
Misguided Use of Hydroxychloroquine for COVID-19: The Infusion of Politics Into Science (2020-11-09)