Searching Strategy and Study Screening Process

We conducted a systematic review on the possibilities of reactivation and reinfection of SARS-CoV-2 in recovered patients that covered published peer-reviewed articles in the literature from Nov 1, 2019, to Mar 29, 2021. Following the guidelines by the “Preferred Reporting Items for Systematic reviews and meta-Analyses” (PRISMA) (34), we searched the following databases: MEDLINE; PubMed; and Embase for papers published in English, among which only human participants were studied. Our search strategy includes (severe acute respiratory syndrome coronavirus 2 OR SARS-CoV-2 OR 2019-nCoV OR coronavirus disease 2019 OR COVID-19) AND (reinfection OR reactivation OR relapse OR RNA shedding OR viral shedding OR re-detectable positive) AND (recovered patients OR discharge patients OR post-COVID-19 patients). Related references were also searched through preprint servers (bioRxiv and medRxiv) and general google search, and reviewing the reference list of the included articles. Letters to editors and commentaries were also included to ensure robust coverage of the existing literature. All retrieved records were imported into the ENDNOTE citation software and duplicates were removed using the ENDNOTE built-in “Find Duplicates” feature. Finally, the titles, abstracts, and full text of the generated studies were sequentially screened to ascertain the studies that met the inclusion criteria of the review.