Comparison of Epidemiologic and Clinical COVID-19 Profiles in Children in Argentina, During Circulation of Original and Variant (Alpha, 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 epidemiologic and clinical features of COVID-19 infection in children under 18 years of age in Argentina, comparing the periods before and after the 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, Delta 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 neurologic 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. 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.

A poor and delayed anti-SARS-CoV2 IgG response is associated to severe COVID-19 in children.

BACKGROUND: Most children and youth develop mild or asymptomatic disease during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, a very small number of patients suffer severe Coronavirus induced disease 2019 (COVID-19). The reasons underlying these different outcomes remain unknown. METHODS: We analyzed three different cohorts: children with acute infection (n=550), convalescent children (n=138), and MIS-C (multisystem inflammatory syndrome in children, n=42). IgG and IgM antibodies to the spike protein of SARS-CoV-2, serum-neutralizing activity, plasma cytokine levels, and the frequency of circulating Follicular T helper cells (cTfh) and plasmablasts were analyzed by conventional methods. FINDINGS: Fifty-eight percent of the children in the acute phase of infection had no detectable antibodies at the time of sampling while a seronegative status was found in 25% and 12% of convalescent and MIS-C children, respectively. When children in the acute phase of the infection were stratified according disease severity, we found that contrasting with the response of children with asymptomatic, mild and moderate disease, children with severe COVID-19 did not develop any detectable response. A defective antibody response was also observed in the convalescent cohort for children with severe disease at the time of admission. This poor antibody response was associated to both, a low frequency of cTfh and a high plasma concentration of inflammatory cytokines. INTERPRETATION: A weak and delayed kinetic of antibody response to SARS-CoV-2 together with a systemic pro-inflammatory profile characterize pediatric severe COVID-19. Because comorbidities are highly prevalent in children with severe COVID-19, further studies are needed to clarify their contribution in the weak antibody response observed in severe disease. FUNDING: National Agency for Scientific and Technological Promotion from Argentina (IP-COVID-19-0277 and PMO-BID-PICT2018-2548).

[Consensus on treatment of multisystemic inflammatory syndrome associated with COVID-19]. / Consenso sobre el tratamiento del síndrome inflamatorio multisistémico asociado a COVID-19.

The pandemic caused by the SARS-CoV-2 virus declared by the WHO in March 11th 2020, affects a small number of pediatric patients, who mostly present mild respiratory compromise and favorable evolution. However began to be observed in previously healthy children, an increase in cases defined as "Multisystemic Inflammatory Syndrome" (MIS-C) or "Kawasaki-like" post-COVID 19 (KLC) that evolve to shock and require hospitalization in the Pediatric Intensive Care Unit. MIS-C and KL-C are characterized by fever; signs of inflammation, gastrointestinal symptoms, and cardiovascular dysfunction, associated with sever forms of presentation with higher incidence of hypotension and/or shock. In the laboratory, markers of inflammation, hypercoagulability and myocardial damage are observed. Firstline drug treatment consists of intravenous immunoglobulin plus oral acetylsalicylic acid. A multidisciplinary approach is recommended for an accurate diagnosis and an early and effective treatment, in order to reduce morbidity and mortality.

La pandemia ocasionada por el nuevo coronavirus (SARS-CoV-2), declarada por la Organización Mundial de la Salud OMS) en marzo de 2020, afecta a un reducido número de pacientes pediátricos, quienes presentan, en su mayoría, compromiso respiratorio leve y evolución favorable. Sin embargo, en niños previamente sanos, comenzó a observarse un aumento de casos definidos como síndrome inflamatorio multisistémico (SIM-C) o similar a Kawasaki (Kawasaki-like) asociado a la enfermedad por el nuevo coronavirus (COVID-19) (KL-C) que evolucionan al shock y requieren internación en la unidad de cuidados intensivos. Los cuadros de SIM-C y los KL-C se caracterizan por fiebre, signos de inflamación, síntomas gastrointestinales y disfunción cardiovascular; las formas graves de presentación tienen mayor incidencia de hipotensión y/o shock. En el laboratorio se observan marcadores de inflamación, hipercoagulabilidad y daño miocárdico. El tratamiento farmacológico de primera línea consiste en la administración de inmunoglobulina por vía intravenosa más ácido acetilsalicílico por vía oral. Se recomienda un abordaje multidisciplinario para un diagnóstico certero y un tratamiento temprano y eficaz para disminuir la morbimortalidad.

Blood neutrophils from children with COVID-19 exhibit both inflammatory and anti-inflammatory markers.

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).