Abstract
The aim of the systematic review is to describe clinical features of coronavirus disease 2019 (COVID-19) in children with a focus on the possible reasons why children are less susceptible to COVID-19 and whether their immune response works better than adults. The three research questions below were determined. (1) Why do pediatric COVID-19 cases have milder clinical symptoms than adults? (2) What are clinical manifestations, diagnosis, and treatment of COVID-19 in children? (3) How long lasts viral shedding after recovery? We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Cochrane Database of Abstracts of Reviews of Effects, as well as foreign literature with English translations. Extra information and data have been collected from Google Scholar and the American Society for Microbiology. Information on patients' age, comorbidities, methods of treatment, and effects on mortality and morbidity were extracted. It is concluded that children are less susceptible to COVID-19 than adults and that the symptoms in children are less severe than in adults. A low incidence of COVID-19 in children and milder disease than in adults might be attributed to many theories and reasons; however, the mechanisms involved are not fully understood.