Lopinavir/ritonavir treatment
LPV/r (400 mg and 100 mg, orally, twice daily) was administered to the laboratory-confirmed cases at the discretion of the attending physicians at every isolation ward. The treatment duration was ≥10 days, according to the recommendations from the Chinese management guideline for COVID-19 (sixth version) [10]. Exposure to LPV/r was defined as having received at least one dosage of LPV/r.