Database of all HCQ COVID-19 studies. 237 studies, 171 peer reviewed, 195 comparing treatment and control groups. Submit updates/corrections below. HCQ is not effective when used very late with high dosages over a long period (RECOVERY/SOLIDARITY), effectiveness improves with earlier usage and improved dosing. Early treatment consistently shows positive effects. Negative evaluations typically ignore treatment time, often focusing on a subset of late stage studies.