IntroductionSARS-CoV-2 virus infection was first reported in China in late 2019 and has spread rapidly around the world. There is little information about the peculiarities of COVID-19 infection in children because the number of infected children was small, around 2% of all diseases.MethodsIn this retrospective study, we recruited 143 children infected with SARS-CoV-2 between March and October 2020, in Sibiu, Romania. RT-PCR tests, serum SARS-CoV-2 IgG/ IgM antibodies, lung radiography, biochemical and hematological tests were performed during the hospitalization.ResultsOf the 143 children selected in the study, 47.0% were male and 53% were female. At admission, all children tested positive for SARS-CoV-2, collecting nasopharyngeal exudate.Clinical manifestations included: cough in 75.52% of cases, fever in 55.94% of cases, nasal obstruction in 50.34% of cases, rhinorrhea in 38.46% of cases, muscle pain in 26.57% of cases, fatigue in 17.48% of cases, diarrhea and headache in 14.68% of cases. In 21 children (14,68%), the number of leukocytes was increased. In 38 cases (26,57%), the lung radiograph showed changes similar to bronchopneumonia, and the other cases did not have pulmonary changes. The persistence of the virus in the body of infected children is above the average reported in studies performed in adults, the virus being identified in the respiratory tract between 16 and 34 days. IgG class antibodies in patients' serum appeared between the 4th day of hospitalization and up to a maximum of 25 days, with a mean of 16.5 days.ConclusionThe persistence of the virus in the body of infected children is above the average reported in studies performed in adults, the virus being identified in the respiratory tract between 16 and 34 days. IgG class antibodies in patients' serum appeared within a mean of 16.5 days. All children were treated with symptomatic support without complications.