2 For example, having 17 infections among several thousand individuals at risk may indeed be consistent with some protective effect of hydroxychloroquine. Notwithstanding occupation and travel, presently, the risk of exposure to the virus differs from one geographical location to another, even within each country. The denominator of all patients with lupus on hydroxychloroquine who are ‘at risk’ of COVID-19 in this setting is unknown and may indeed be impossible to even estimate as it would need to be adjusted for risk of exposure to SARS-CoV-2. While the authors have correctly acknowledged the limitations of this case series report, we wish to emphasise several important points that impact the interpretation of the findings. 1 In a context where there is substantial interest in the role of hydroxychloroquine (HCQ) as a potential preventive or therapeutic agent for severe acute respiratory syndrome–coronavirus-2 (SARS-CoV-2), these cases are noteworthy.
We thank Mathian et al for reporting the outcomes of COVID-19 disease in a series of 17 patients with systemic lupus erythematosus (SLE) from several hospitals across France.
