Source: C19Study
A live and ongoing index of studies from around the world documenting the use of hydroxychloroquine in treatment at various stages of SARS-CoV-2 infection including pre-exposure prophylaxis and post-exposure prophylaxis is available at https://c19study.com/, that also states whether the outcome was positive or negative.
Overwhelmingly, PrEP, PEP, and early treatment studies show high effectiveness of hydroxychloroquine, while late treatment shows mixed results.
Older Updates can be found here:
61 studies (37 peer reviewed) Early treatment studies are very positive – COVID deaths: 621, 206
Related:
Belgium Study 8,075 patients: Low HCQ doses resulted in lower mortality in Covid patients