**René Hage 1,2, Carolin Steinack 1,2, Christian Benden 2,3 and Macé M. Schuurmans 1,2,\***


Received: 9 April 2020; Accepted: 4 May 2020; Published: 7 May 2020

**Abstract:** The novel coronavirus, SARS-CoV-2, is causing a pandemic of unknown precedent, with huge healthcare challenges and worldwide disruptions to economic and social life. Lung transplant recipients and other solid organ transplant (SOT) recipients are immunosuppressed, and therefore are generally considered at an increased risk for severe infections. Given the current gap in knowledge and evidence regarding the best management of these patients, we conducted a systematic review of studies on SARS-CoV-2 infections and Coronavirus Disease 2019 (COVID-19) in SOT recipients, to evaluate the association between immunosuppression in these patients, SARS-CoV-2 infection and COVID-19 outcomes. The focus was the severity of the disease, the need for mechanical ventilation and intensive care unit (ICU) admissions, and rate of death. The literature search was conducted repeatedly between 16 March and 8 April 2020. We searched original papers, observational studies, case reports, and meta-analyses published between 2019 and 2020 using two databases (PubMed, Google Scholar) with the search terms: [transplant OR immunosuppression] AND [COVID-19 OR SARS-CoV-2]. Further inclusion criteria were publications in English, French, German and Italian, and reference to humans. We also searched the reference lists of the studies encountered. From an initial search of PubMed and Google Scholar, 19 potential articles were retrieved, of which 14 were excluded after full-text screening (not being case reports or case series), leaving 5 studies for inclusion. No further studies were identified from the bibliographies of retrieved articles. Based on the limited research, no firm conclusions can be made concerning SOT recipients, but the current evidence suggests that immunosuppression is most likely associated with a better outcome of SARS-CoV-2 infection and COVID-19 because it prevents hyperinflammation (cytokine storm) in this particular population. There is a need for further research that would allow results to be adjusted for other factors potentially impacting COVID-19 severity and outcome.

**Keywords:** SARS-CoV-2; coronavirus; immunosuppression; tacrolimus; corticosteroids; mycophenolate mofetil; hyperinflammation; cytokine storm; pandemic; transplantation
