**3. Methods**

This systematic review was conducted with reference to the basics of Cochrane Handbook for Systematic Reviews of Interventions [19], described as stated by the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) statement [20].

#### *3.1. Search Strategy and Selection Criteria*

A systematic review protocol was developed based on PRISMA-P and the PRISMA statement. Published articles from 1 December 2019, to 20 November 2020, were selected for review from 8 electronic databases (PubMed, CINAHL, Embase, medRxiv, Proquest, Wiley online library, Medline, and Nature).

The focus of the review was LPV/RTV treatment in COVID-19 patients. The primary outcome was the efficacy of LPV/RTV in COVID-19 patients. The secondary outcome was adverse events associated with its use.

### *3.2. Inclusion Criteria*

Readily accessible peer-reviewed full articles, observational cohort studies, and clinical trials were included.
