Comparison of Epidemiological and Clinical COVID-19 Profiles in Children in Argentina, During Circulation of Original and Variant (Alfa, Gamma and Lambda) Strains

Background: Information on the impact of the different variants in children in Latin America is scarce. The objective of this study was to describe epidemiological and clinical features of COVID-19 infection in children under 18 years of age in Argentina, comparing the periods before and after circulation of new variants.Methods: Observational, cross-sectional, multicentric, analytical study. All patients under 18 years of age with confirmed SARS-CoV-2 infection admitted at 22 healthcare centers were included. Two study periods were established: Period 1 (EW10-2020 to EW12-2021) for the Wuhan strain; Period 2 (EW13 to EW35 2021) for Alpha, Gamma, and Lambda variants.Findings: A total of 6330 confirmed cases were included. Period 1: 3575 (56.5%), period 2: 2755 (43.5%). During period 2, a lower number of asymptomatic cases was observed, while general, respiratory and neurological signs and symptoms increased in all age groups. Oxygen therapy requirement was higher during the first period (36.7% vs 19.1%; p<0.001). No significant differences were observed in the rates of severe or critical cases (6.3% vs 5,4%; p=0.102), intensive care admission (2.1% vs 2%; p<0.656) or case fatality (0.3% vs 0.5%; p<0.229). MIS-C cases occurred more frequently during the first period (1.9% vs 1.1%; p=0.009). Interpretation: The clinical spectrum of COVID-19 in Argentina has evolved over time. With the emergence of new variants, although the number of asymptomatic cases declined, numbers of severe and critical cases, as well as case fatality rates in children, remained unchanged.Funding: None to declare. Declaration of Interest: The Authors declare no competing interestsEthical Approval: The study was first approved by the Research and Ethics Boards at each participating site.