Cases of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have increased dramatically since December 2019 evolving into the current COVID-19 pandemic. Adults, in particular the elderly, constitute the majority of cases and, overwhelmingly, of fatalities. A small proportion of cases have been children and young people, and generally manifestations in children are mild, with few complications and deaths reported (Ahmed et al, 2020). During the early stages of the pandemic, an unusual constellation of clinical manifestations, now called multisystem inflammatory syndrome in children (MIS-C), was recognised in small numbers of young patients. MIS-C was noted to be temporally related to COVID-19 and presented around 3-4 weeks after acute SARS-CoV-2 infection; a causal link has yet to be confirmed (Ahmed et al, 2020). The clinical manifestation of MIS-C includes shock and multisystem dysfunction, occasionally leading to death. There is significant clinical overlap with other widespread, severe conditions, such as Kawasaki disease and toxic shock syndrome, potentially creating diagnostic difficulty (Ahmed et al, 2020). The typical presenting symptoms of MIS-C are fever, rash, abdominal pain, diarrhoea and vomiting. Low blood pressure, shock, and cardiac abnormalities are common physical signs. Laboratory investigations usually show abnormal blood findings suggestive of severe inflammation—including high neutrophil count, elevated C-reactive protein and low lymphocyte count (Ahmed et al, 2020; Swann et al, 2020).
A systematic review including 39 observational studies with 662 children presenting with symptoms of MIS-C found that many did not have a positive PCR test for SARS-CoV-2 (Ahmed et al, 2020). Many patients had antibodies showing that they had at some point been infected with SARS-CoV-2 or reportedly had previously had positive microbiological investigations for the virus. Very few of the children in these studies presented to hospital for the initial SARS-CoV-2 infection, and in fact many experienced no initial symptoms at all.
A UK-based study reported that older children (median age 10.7 years) were at higher risk of developing MIS-C (Swann et al, 2020). The systematic review by Ahmed et al (2020) found that 71% of these children required intensive care admission, and 11 of them died. Swann et al (2020) reported 651 children were admitted to hospital with SARS-CoV-2, of whom 52 later developed MIS-C. These children were five times more likely to be admitted to critical care, and many needed mechanical ventilation, intravenous immunoglobulins, steroids and a multidisciplinary approach for their management (Swann et al, 2020).
Discussions about the relation of ethnicity to severity of symptoms have been a developing theme of the pandemic. A high proportion of patients from black, Asian and minority ethnic (BAME) backgrounds have had more severe outcomes from SARS-CoV-2. Studies have shown that 62–71% of patients with MIS-C are of non-white descent (Ahmed et al, 2020; Rao and Sandhu, 2020; Swann et al, 2020). This may suggest a potential genetic component to the pathogenesis of MIS-C, and the possible contribution of socioeconomic factors to the severity of COVID-19 in children. Although further research is needed to confirm the causality with SARS-CoV-2 and MIS-C, the link between BAME children and increased incidence and worse prognosis with MIS-C is evident and needs consideration in clinical practice (Rao and Sandhu, 2020). Health professionals on the frontline should be aware of the delayed complications of SARS-CoV-2 infection, particularly in those from BAME background presenting with any symptoms suggestive of MIS-C. If a child presents with signs and symptoms of MIS-C after a possible SARS-CoV-2 infection, an early multidisciplinary team approach is indicated, including critical care.