In this prospective longitudinal cohort the investigators reported the clinical, and biological characteristics of all critically ill patients admitted in the pediatric intensive care unit (PICU) of Bicêtre Hospital during the 2019 coronavirus disease (COVID-19) pandemics. Patients were older than 37 weeks of gestational age. No upper limit was set as the unit was transiently converted into a pediatric "adult COVID-19" intensive care unit.

All patients will be monitored during their PICU stay.

Clinical characteristics include: age, gender, co-morbidities, organ support therapies (mechanical ventilation, renal replacement therapy, extracorporeal membrane oxygenation, vasopressors), organ complications (pulmonary embolism, acute respiratory distress syndrome, renal failure, heart failure) and function, infective complications (ventilator associated pneumonia, central line associated bloodstream infection, pulmonary access, sepsis, septic shock), microbiologic and viral identification, 7-day and 28-day mortality.

Biological characteristics include:

• Admission workup: qualitative and quantitative Ig, ferritin, creatinine kinase, complement study (C3,C4,CH50),
• Daily workup: blood cells count, arterial blood gas analysis, lactate, electrolytes, albumin, blood urea nitrogen, creatinine, hemostasis (fibrinogen, factor V, II+VII, factor X, prothrombin time, antiXa activity, activated cephalin time, D-dimer), C-reactive protein, procalcitonin.
• Twice weekly workup: circulating cells phenotyping (T cell and subclass including Treg, B cell, Natural Killer cell, myeloid derived suppressor cell, neutrophils), interleukin 6.
• Bone marrow analysis when indicated by attending staff.

Inclusion Criteria:

• Patients suspected or confirmed of severe acute respiratory syndrome Coronavirus 2 infection
• No opposition from patients or legal representatives after study information
• Patients admitted to the pediatric intensive care unit of Bicêtre Hospital, Assistance Publique Hôpitaux de Paris - Paris Saclay University
• Between March 15, 2020 to June 31, 2021

Exclusion Criteria:

• Patient or legal representative refusal to participate

Most patients admitted in the PICU of Bicêtre Hospital are children <18 years old. Adults critically ill patients with COVID-19 were admitted in case of patients overflow in adult Intensive Care Unit.