Transmission of Coronavirus (SARS-CoV-2) by Presymptomatic and Asymptomatic COVID-19 Carriers: A Systematic Review

Abstract

To mitigate the spread of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), many efforts have been made including the adoption of non-pharmaceutical measures such as hand hygiene, wearing of face mask, and social distancing. Sadly, the absence of symptoms in some SARS-CoV-2 carriers has impeded the success of these current interventions, and the number of COVID-19 cases continues to increase globally. Understanding the impact and pattern of transmission by presymptomatic and asymptomatic cases is crucial to the management of the disease. We aimed to review the transmission or spread of COVID-19, to provide insight into the impact of these silent spreaders, and inform public health policymaking. A systematic review of published articles was conducted. PubMed, Google Scholar, and Science Direct were searched for articles published in the English Language from January to July 2020. A total of 20 articles were found eligible for the review based on the predetermined inclusion and exclusion criteria. 17 articles, of which 13 were case reports, 1 serial interval report, 2 investigational reports, and 1 modeling study, provided evidence of asymptomatic and presymptomatic transmission. 3 articles reported on the quantitative contribution of asymptomatic and presymptomatic transmission. Evidence provided in the literature is not sufficient to elucidate the impact and relative contribution of asymptomatic and presymptomatic SARS-CoV-2 carriers on the spread of the disease. Strengthening of the current non-pharmaceutical measures or better still adoption of other innovative approaches is crucial to combating COVID-19 as far as presymptomatic and asymptomatic cases are concerned.