Background Perhaps reflecting that children with COVID-19 rarely exhibit severe respiratory symptoms and often remain asymptomatic, little attention has been paid to explore the immune response in pediatric COVID-19. Here, we analyzed the phenotype and function of circulating neutrophils from children with COVID-19. Methods An observational study including 182 children with COVID-19, 21 children with multisystem inflammatory syndrome (MIS-C), and 40 healthy children was performed in Buenos Aires, Argentina. Neutrophil phenotype was analyzed by flow cytometry in blood samples. Cytokine production, plasma levels of IgG antibodies directed to the spike protein of SARS-CoV-2 and citrullinated histone H3 were measured by ELISA. Cell-free DNA was quantified by fluorometry. Findings Compared with healthy controls, neutrophils from children with COVID-19 showed a lower expression of CD11b, CD66b, and L -selectin but a higher expression of the activation markers HLA-DR, CD64 and PECAM-1 and the inhibitory receptors LAIR-1 and PD-L1. No differences in the production of cytokines and NETs were observed. Interestingly, the expression of CD64 in neutrophils and the serum concentration of IgG antibodies directed to the spike protein of SARS-CoV-2 distinguished asymptomatic from mild and moderate COVID-19. Interpretation Acute lung injury is a prominent feature of severe COVID-19 in adults. A low expression of adhesion molecules together with a high expression of inhibitory receptors in neutrophils from children with COVID-19 might prevent tissue infiltration by neutrophils preserving lung function. Funding This study was supported by the Ministry of Science and Technology (National Agency for Scientific and Technological Promotion, IP-COVID-19-0277 and PMO BID PICT 2018-2548), and University of Buenos Aires from Argentina (20020170100573BA).

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Background: Perhaps reflecting that children with COVID-19 rarely exhibit severe respiratory symptoms and often remain asymptomatic, little attention has been paid to explore the immune response in pediatric COVID-19. Here, we analyzed the phenotype and function of circulating neutrophils from children with COVID-19. Methods: An observational study including 182 children with COVID-19, 21 children with multisystem inflammatory syndrome (MIS-C), and 40 healthy children was performed in Buenos Aires, Argentina. Neutrophil phenotype was analyzed by flow cytometry in blood samples. Cytokine production, plasma levels of IgG antibodies directed to the spike protein of SARS-CoV-2 and citrullinated histone H3 were measured by ELISA. Cell-free DNA was quantified by fluorometry. Findings: Compared with healthy controls, neutrophils from children with COVID-19 showed a lower expression of CD11b, CD66b, and L-selectin but a higher expression of the activation markers HLA-DR, CD64 and PECAM-1 and the inhibitory receptors LAIR-1 and PD-L1. No differences in the production of cytokines and NETs were observed. Interestingly, the expression of CD64 in neutrophils and the serum concentration of IgG antibodies directed to the spike protein of SARS-CoV-2 distinguished asymptomatic from mild and moderate COVID-19. Interpretation: Acute lung injury is a prominent feature of severe COVID-19 in adults. A low expression of adhesion molecules together with a high expression of inhibitory receptors in neutrophils from children with COVID-19 might prevent tissue infiltration by neutrophils preserving lung function.

Introduction. Changes in daily routine and social fabric resulting from the COVID-19 pandemic had an effect on children and adolescents. The objective of this study was to know the mood, emotions, and behaviors of children and adolescents during the COVID-19 lockdown. Population and methods. This was a prospective, descriptive, cross-sectional study. Parents and/ or caregivers of children and adolescents aged 3-15 years in the Autonomous City of Buenos Aires were asked about their perceptions of the mood, behaviors, and emotions of children and adolescents during the lockdown. Results. A total of 1080 questionnaires were included. Results showed that 81% of parents and/or caregivers observed changes in children and adolescents emotional health; 76% referred that children aged 3-5 years were bored, angry, and upset. They also observed an increase in crying spells (52%) and regression to behaviors that had been outgrown (29%). In the 6-11-year-old group, 43% showed difficulty focusing. Adults noticed that 3 out of 10 adolescents aged 12-15 years discontinued activities they used to enjoy and were sad and worried. Conclusion.The COVID-19 pandemic impacted on the mood, behaviors, and emotions of children and adolescents. Negative feelings prevailed, such as boredom, sadness, anxiety, and worry.

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