Retrospective PrEP analysis with 69 healthcare workers on PrEP HCQ, and 418 control.Authors report PCR and IgG results, with no baseline results for either. Authors note they "identified 69 HCWs receiving HCQ" while providing no information as to why or when they started HCQ.No conclusions can be drawn from this study because many workers may have been positive before starting HCQ. Only 14% of workers chose to use HCQ and they may have been motivated to do so because they had an infection.Authors perform several different adjustments, finding very different results. No information on death, hospitalization, symptoms, or severity is provided. Details on timing of serology and baseline serology status is not provided. Potential bias due to self-selection for risk.25% of infections were detected before 7 days, indicating that they actually happened earlier (PCR false positive is very high initially). It is likely that many infections were before HCQ could reach therapeutic levels.