TGFB1 and COVID-19: TGFβ1 serum levels in patients with MIS-C (median: 398 pg ml−1) resembled those in adults who were severely affected by COVID-19 (median: 415 pg ml−1, P ≥ 0.9999) and were approximately 3-fold higher than those in non-infected children (median: 132.2 pg ml−1), 2.6-fold higher than during acute SARS-CoV-2 infection (median: asymptomatic/mild, 150.1 pg ml−1; moderate/severe, 150.7 pg ml−1) and 7-fold higher than in paediatric controls at 6 wpi without MIS-C (6 wpi no MIS-C median: 63 pg ml−1, P = 0.0018) or in healthy young adults (median: 64 pg ml−1, P = 0.0003).