Non-Multisystem Inflammatory Syndrome in Children—Postacute Sequelae of Paediatric COVID-19: Autoimmune or Autoinflammatory? A Systematic Review of the Reported Cases

Abstract

Three years after its emergence, coronavirus disease 2019 (COVID-19) continues to be a leading cause of worldwide morbidity and mortality. This systematic review comprises relevant case reports that discuss non-multisystem inflammatory syndrome in children (non-MIS-C) and postacute sequalae of COVID-19 (PASC) in the paediatric population, also known as long COVID syndrome. The study aims to highlight the prevalent time interval between COVID-19 and the development of non-MIS-C post-infectious sequalae (PIS). Databases were searched for studies that met our inclusion and exclusion criteria. The final screening revealed an equal sex distribution where the commonest age intervals were school-age and adolescence, with 38% of the patients being older than six years. Interestingly, hospital admission during the course of COVID-19 was not a predictor of the subsequent PASC; forty-nine patients (44.9%) were hospitalized while sixty patients (55.1%) were not hospitalized. Moreover, the most predominant time interval between COVID-19 and the developing PASC was within 14 days from the start of COVID-19 infection (61%). These findings suggest a crucial link between COVID-19 and immune PIS in the paediatric population, especially those older than six years. Accordingly, follow-up and management are encouraged in case of unusual symptoms and signs following COVID-19 infection, regardless of the COVID-19 infection severity.