• HCQ is effective for COVID-19. The probability that an ineffective treatment generated results as positive as the 195 studies to date is estimated to be 1 in 1 quadrillion (p = 0.0000000000000009).• Early treatment is most successful, with 100% of studies reporting a positive effect and an estimated reduction of 67% in the effect measured (death, hospitalization, etc.) using a random effects meta-analysis, RR 0.33 [0.25-0.43].• 91% of Randomized Controlled Trials (RCTs) for early, PrEP, or PEP treatment report positive effects, the probability of this happening for an ineffective treatment is 0.0059.• There is evidence of bias towards publishing negative results. 88% of prospective studies report positive effects, and only 75% of retrospective studies do.• Studies from North America are 4.0 times more likely to report negative results than studies from the rest of the world combined, p = 0.00000005.

Total	195 studies	3,074 authors	166,999 patients
Positive effects	152 studies	2,394 authors	123,307 patients

Early treatment	67% improvement	RR 0.33 [0.25-0.43]
Late treatment	25% improvement	RR 0.75 [0.69-0.81]