On Apr. 6, 2020, a trial led by the Perelman School of Medicine at the University of Pennsylvania was announced to evaluate whether the drug hydroxychloroquine (HCQ) can benefit people infected with COVID-19, as well as whether taking the drug preventatively may help people avoid infection altogether.

PATCH substudy 1 will evaluate HCQ compared to placebo in infected patients who are quarantined at home. PATCH substudy 2 will evaluate high dose compared to low dose HCQ in hospitalized patients. PATCH sub-study 3 will evealuate HCQ compared to placebo prophylactically in health care workers working with COVID-19 patients to evaluate whether it can prevent infection.

Substudies 1 and 3 are double-blind placebo controlled studies, meaning neither the patient nor the doctor will know whether they are taking HCQ or placebo until the end of the study. Importantly, if the patient or health care worker starts getting worse, they can be “unblinded”, and the trial allows crossover to HCQ if the patient was assigned placebo.