Background. In Germany over 80% of children and adolescents are in the ambulatory care of registered pediatricians. These have a specific perspective on the COVID-19 pandemic. Methods. For this reason, this professional group initiated a central recording of case numbers, individual case descriptions and observations on infections and illnesses with SARS-CoV-2 (www.co-ki.de). Results. So far 557 pediatricians have participated. Together they care for ca. 670,000 children. They reported 9803 children who presented as suspected cases. The pediatricians themselves had a clinical suspicion of SARS-CoV-2 infections in 3654 children. In 7707 children PCR tests were carried out using nose/throat swabs of which 198 (2.6%) were positive. In addition, 731 children were tested for SARS-CoV-2 antibodies with detection in 82 cases (11.2%). Despite initially positive PCR tests, 47 children had a negative antibody test at least 2 weeks later. Our query as to infections of adults by children yielded only one case, which a telephone enquiry revealed as unlikely. Discussion. From an outpatient pediatric perspective COVID-19 is rare. There was no convincing evidence that children are a relevant source of infection for SARS-CoV-2 nor that they are relevantly at risk.

In patients infected by SARS-CoV-2 who experience an exaggerated inflammation leading to pneumonia, monocytes likely play a major role but have received poor attention. Thus, we analyzed peripheral blood monocytes from patients with COVID-19 pneumonia and found that these cells show signs of altered bioenergetics and mitochondrial dysfunction, had a reduced basal and maximal respiration, reduced spare respiratory capacity, and decreased proton leak. Basal extracellular acidification rate was also diminished, suggesting reduced capability to perform aerobic glycolysis. Although COVID-19 monocytes had a reduced ability to perform oxidative burst, they were still capable of producing TNF and IFN-gamma in vitro. A significantly high amount of monocytes had depolarized mitochondria and abnormal mitochondrial ultrastructure. A redistribution of monocyte subsets, with a significant expansion of intermediate/pro-inflammatory cells, and high amounts of immature monocytes were found, along with a concomitant compression of classical monocytes, and an increased expression of inhibitory checkpoints like PD-1/PD-L1. High plasma levels of several inflammatory cytokines and chemokines, including GM-CSF, IL-18, CCL2, CXCL10, and osteopontin, finally confirm the importance of monocytes in COVID-19 immunopathogenesis.