2 Materials and Methods

To conduct this rapid review, we employed abbreviated systematic review methods. Compared with the methods of a systematic review, the review team applied the following methodological shortcuts for this rapid review:
• No searches in trial registries
• Only 30% of abstracts were dually screened
• No dual independent risk of bias assessment and rating of the certainty of evidence; one investigator conducted the ratings, a second investigator checked the plausibility and correctness. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) throughout this manuscript.18

2.1 Literature search

An experienced information specialist conducted a systematic search of the literature published in English or German from January 1, 2002 to February 12, 2020 in Ovid MEDLINE, the WHO Global Index Medicus, Embase (Elsevier), and CINAHL (Cumulative Index to Nursing and Allied Health Literature) (Ebsco). A second information specialist reviewed the MEDLINE search strategy. Annex A presents the detailed search strategies.
In addition, WHO provided a list of citations and abstracts from articles published in Chinese-language journals that was prepared by the WHO Collaborating Centre for Guideline Implementation and Knowledge Translation, Lanzhou, China. Manual searches of selected international journals as well as searches of the following bibliographic databases were conducted: CNKI (China National Knowledge Infrastructure), Embase.com (Elsevier), PubMed. For articles published in Chinese only, the Collaborating Centre prepared an English translation of the abstracts. If no abstract was available, the Collaborating Centre provided a “Brief Summary” in English. This list was updated on a daily basis. The last date of the search considered for this review was February 16, 2020. One team member of the WHO Collaborating Centre in Austria searched a WHO database19 containing results of daily literature searches on COVID-19 (up to February 16, 2020). In addition, review authors screened reference lists of systematic reviews on quarantine in general, and included studies for additional relevant citations.

2.2 Eligibility criteria

Table 1 presents the inclusion and exclusion criteria. The WHO expert panel selected four outcomes that they deemed relevant for their decision-making process: outward transmission, incident cases of COVID-19, mortality, and resource use. We graded the certainty of evidence for these outcomes. We report on other patient-relevant outcomes in the Results section, but we did not grade the certainty of evidence.
Table 1. Inclusion and Exclusion Criteria of the Rapid Review