Cochrane corner: universal screening for SARS-CoV-2 infection

Introduction: coronavirus disease 2019 (COVID-19) is caused by the novel coronavirus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Most people infected with SARS-CoV-2 have mild disease with non-specific symptoms, although a few becoming critically ill with septic shock and multiple organ failure. There is an unknown proportion of infected individuals who remain asymptomatic and infectious. Universal screening for COVID-19 infections to detect individuals who are infected before they present clinically could therefore be an important measure to contain the spread of the disease. We highlight a Cochrane rapid review which assessed the effectiveness and accuracy of universal screening for COVID-19 infection. Methods: the authors of the Cochrane review searched multiple electronic databases to identify studies reporting on the effectiveness of universal screening and reporting on screening test accuracy. Eligible participants for the review included people who had not sought care for potential COVID-19 symptoms. Results: the authors included 22 publications, with none of them conducted in Africa. Two modelling studies reported on the beneficial and negative effects of screening; and 20 studies (cohort and modelling) reported data on the accuracy of screening tests. The included studies had wide variability in the baseline prevalence of COVID-19 infection as well as study settings and methods. All cohort studies compared screening strategies to reverse transcriptase-polymerase chain reaction (RT-PCR) as the gold standard. The rapid review suggests that there is low certainty of evidence that screening at travel hubs may slow the importation of infected cases. Furthermore, the review highlights the uncertainty and variation in the accuracy of screening. Conclusion: given the low accuracy of the tests included in this review, a high proportion of COVID-19 infected individuals may be missed and go on to infect others. In addition, some healthy individuals may be falsely identified as positive, requiring confirmatory testing and potentially leading to the unnecessary isolation of these individuals.