to adjust for baseline differences between patients on HCQ, it is possible that unmeasured confounders were not accounted for, resulting in residual treatment selection bias. Moreover, our cohort was predominantly female (85.4%), reflecting the gender predilection of cicatricial alopecia. Nonetheless, the strength of our study draws from our relatively healthy patient cohort. In contrast to other studies that have attempted to gauge susceptibility of patients on chronic HCQ to COVID-19 infection,8 only a minority of our patient cohort (13.9%) demonstrated comorbid autoimmune disease. Thus, our study represents one of the first analyses of HCQ as potential PrEP for COVID-19 infection in patients that faithfully recapitulate a generally healthy population. While our sample size is limited, the evidence suggests HCQ may have some benefit, though further RCTs are warranted.
