Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test could be positive for a second time in some cases, after recovery from their first coronavirus disease 2019 (COVID-19) episode. However, causes of this re-positive test has not been fully understood. In this paper, the original studies with re-positive COVID-19 patients in their study population were discussed. Methods: Scopus, PubMed, Embase, and Cochrane databases were searched and the retrieved records underwent title/abstract and full-text screenings. Three independent researchers extracted the data of the studies. Results: The systematic search yielded 16 case-control, cohort, and cross-sectional studies. Data of 10,475 patients were included; 489 (4.67%) of them classified as re-positive. The female percentage and mean age for re-positive and non-re-positive groups were 56.82% and 50.0 ± 18.0, and 55.91% and 46.6 ± 17.1, respectively. The rate of symptom presentation upon second positive test turned out to be 20.0%, with the most common symptoms being cough (68.2%), fever (31.8%), and fatigue (22.7%). Hypertension (15.9%) accounted for the most common underlying disease in the re-positive group. In 33/46 (71.7%) of the re-positive patients, computed tomography (CT) abnormalities were resolved to some extent. Conclusion: A re-positive SARS-CoV-2 test is possible within a few weeks after recovery, although it does not necessarily indicate a re-infection. Other reasons could lead to a re-positive test such as reactivation of the virus that persisted in the body from the previous COVID-19 episode and testing errors. Clinical features such as symptoms and imaging could assist in identifying re-infections.
