Methods
We conducted this systematic
review to explore and investigate the validity of reported re-infected
cases worldwide. For this purpose, we carried out systematic research in
Pubmed, Embase, Scopus, and Cochrane databases. We present the final
search strategy with the letter āCā below:
- [reinfection] (Title/Abstract) OR [reinfected]
(Title/Abstract) OR [second infection] (Title/Abstract) OR
[re-positive] (Title/Abstract) OR [re-positive]
(Title/Abstract) OR [recurrent] (Title/Abstract) OR
[recurrence] (Title/Abstract) OR [relapse] (Title/Abstract) OR
[relapsing] (Title/Abstract) OR [persistent PCR positive]
(Title/Abstract) OR [persistent positive PCR] (Title/Abstract)
- [COVID-19] (Title/Abstract) OR [SARS-CoV-2] (Title/Abstract)
OR [Novel Coronavirus] (Title/Abstract) OR [2019-nCoV]
(Title/Abstract)
- [A] AND [B]
Upon retrieving the desired search results, three researchers screened
the articles in a two-step process. The first step of this process
involved general inclusion/exclusion criteria based on the title,
abstract, and keywords of each study.
The main exclusion criteria in this phase were the following:
1) Abstracts and conference-abstracts without full-text articles
2) Ongoing projects and clinical trials yet to be published
3) Lack of published original data, including review articles, or
editorials without providing any original data
4) Case-reports, case-series, and pre-prints
5) Irrelevant to the aims and scope of the study
6) The smaller study in the studies with a high suspect of population
overlap between them
In the second phase, we carefully read through the full-text of the
articles and included the eligible studies. Finally, peer-reviewed
cross-sectional, clinical trials, case-control, and cohort studies from
the beginning of January 2020 until late July 2020 were included in our
study.