EAACI statement on the pathogenesis, immunology, and immune-targeted
management of the Multisystem Inflammatory Syndrome in Children (MIS-C)
or Pediatric Inflammatory Multisystem Syndrome (PIMS).
Abstract
Multisystem inflammatory syndrome in children (MIS-C) is a rare, but
severe complication of coronavirus disease 2019 (COVID-19). It develops
approximately four weeks after severe acute respiratory syndrome
coronavirus 2 (SARS-CoV-2) infection and involves hyperinflammation with
multisystem injury, commonly progressing to shock. The exact
pathomechanism of MIS-C is not known, but immunological dysregulation
leading to cytokine storm plays a central role. In response to the
emergence of MIS-C, the European Academy of Allergy and Clinical
Immunology (EAACI) established a task force (TF) within the Immunology
Section in May 2021. With the use of an online Delphi process, TF
formulated clinical statements regarding immunological background of
MIS-C, diagnosis, treatment, follow-up, and the role of COVID-19
vaccinations. MIS-C case definition is broad, and diagnosis is made
based on clinical presentation. The immunological mechanism leading to
MIS-C is unclear and depends on activating multiple pathways leading to
hyperinflammation. Current management of MIS-C relies on supportive care
in combination with immunosuppressive and/or immunomodulatory agents.
The most frequently used agents are systemic steroids and intravenous
immunoglobulin. Despite good overall short-term outcome, MIS-C patients
should be followed-up at regular intervals after discharge, focusing on
cardiac disease, organ damage, and inflammatory activity. COVID-19
vaccination is a safe and effective measure to prevent MIS-C. In
anticipation of further research, we propose a convenient and clinically
practical algorithm for managing MIS-C developed by the Immunology
Section of the EAACI.