According to The Lancet, hydroxychloroquine is a little worse than useless.
www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31180-6/fulltext
10?698 (11?1%) patients died in hospital. After controlling for multiple confounding factors (age, sex, race or ethnicity, body-mass index, underlying cardiovascular disease and its risk factors, diabetes, underlying lung disease, smoking, immunosuppressed condition, and baseline disease severity), when compared with mortality in the control group (9?3%), hydroxychloroquine (18?0%; hazard ratio 1?335, 95% CI 1?223-1?457), hydroxychloroquine with a macrolide (23?8%; 1?447, 1?368-1?531), chloroquine (16?4%; 1?365, 1?218-1?531), and chloroquine with a macrolide (22?2%; 1?368, 1?273-1?469) were each independently associated with an increased risk of in-hospital mortality.