COVID-19 studies:  C19 studies: C19:  IvermectinIVM Vitamin DV.D HC QHC Q Vitamin CV.C ZincZn PVP-IPVP-I FLVFLV REGNR2 LY-CoVLY RemdesivirRMD
HCQ study #123 of 260
8/27 Pre-Exposure Prophylaxis study (treated before exposed to the virus)
Ferri at al., Clinical Rheumatology, doi:0.1007/s10067-020-05334-7 (Peer Reviewed)
COVID-19 and rheumatic autoimmune systemic diseases: report of a large Italian patients series
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Analysis of 1641 systemic autoimmune disease patients showing csDMARD (HCQ etc.) RR 0.37, p=0.015.
csDMARDs include HCQ, CQ, and several other drugs, so the effect of HCQ/CQ alone could be higher.
This study also confirms that the risk of COVID-19 for systemic autoimmune disease patients is much higher overall, OR 4.42, p<0.001 (this is the observed real-world risk which takes into account factors such as these patients potentially being more careful to avoid exposure).
(results are for "definite + highly suspected" cases and the main result is presented in the paper as the OR for not taking csDMARDs, we have converted this to RR for taking csDMARDs).

Ferri et al., 8/27/2020, retrospective, Italy, Europe, peer-reviewed, survey, 29 authors.
risk of COVID-19 case, 63.0% lower, RR 0.37, p = 0.01, treatment 9 of 994 (0.9%), control 16 of 647 (2.5%).

Effect extraction follows pre-specified rules prioritizing more serious outcomes. For an individual study the most serious outcome may have a smaller number of events and lower statistical signficance, however this provides the strongest evidence for the most serious outcomes when combining the results of many trials.
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