Incidence and Clinical Phenotype of Multisystem Inflammatory Syndrome in Children After Two SARS-CoV-2 Pandemic Waves: A Croatian Prospective Nationwide Study.

This prospective nationwide study in Croatia (March 1, 2020-December 31, 2021) embraced 121 children with multisystem inflammatory syndrome. Incidence rates, disease course and outcomes were similar to those reported from other European countries. The severe acute respiratory syndrome coronavirus 2 virus Alpha strain appeared associated with a higher propensity to result in multisystem inflammatory syndrome in children than the Delta strain but did not appear related to disease severity.

The Impact of Vitamin D Levels on Clinical Manifestations of Multisystem Inflammatory Syndrome in Children: A Cross-Sectional Study.

BACKGROUND: Hyperinflammatory response that resembles Kawasaki disease may develop in children after COVID-19 disease, and it is called multisystem inflammatory syndrome in children. The cause of MIS-C is dysregulated innate immune response and a subsequent cytokine storm that results in endothelial damage. It has been determined that low levels of serum 25(OH)D increase the risk of developing immune-related diseases and disorders. METHODS: To determine the incidence of hypovitaminosis D, and a possible correlation between 25(OH)D levels and the clinical severity of MIS-C, 21 patients hospitalized in the University Hospital of Split due to MIS-C were evaluated. RESULTS: Hypovitaminosis D was detected in 95% of MIS-C patients. We found a significant relationship between the severity of MIS-C and 25(OH)D levels, as patients with more severe MIS-C had lower 25(OH)D. MIS-C patients with lower vitamin D levels had worse systolic and diastolic function of the left ventricle according to echocardiograms. There was no relationship between 25(OH)D levels and the tested laboratory inflammatory and cardiac markers. CONCLUSION: Hypovitaminosis D is very common in children with MIS-C and influences the severity of the disease. VD could be a new potential biomarker in MIS-C, and VD replacement therapy should be considered early on in the treatment of MIS-C.