Effect of pre-exposure use of hydroxychloroquine on COVID-19 mortality: a population-based cohort study in patients with rheumatoid arthritis or systemic lupus erythematosus using the OpenSAFELY platform
Rentsch et al., The Lancet Rheumatology, doi:10.1016/S2665-9913(20)30378-7 (preprint 9/9/2020)
https://c19hcq.org/rentsch.html