Experts reviewed studies of multisystem inflammatory syndrome in children (MIS-C) to understand the typical pattern of this rare post-COVID syndrome.
Studies to date on the SARS-CoV-2 virus that causes COVID-19 disease suggest that children are highly resilient to the infection and usually have either mild respiratory symptoms or are asymptomatic. However, in April 2020, pediatricians in the United Kingdom reported on a small case cluster of a new hyperinflammatory disease in children that appeared to occur following SARS-CoV-2 infection. These children became severely ill and required hospitalization, usually including critical care support. Similar reports began appearing around the world and the condition was called “multisystem inflammatory syndrome in children” (MIS-C). To understand more about the typical symptoms and outcome of MIS-C, child health experts at the University of Texas conducted a comprehensive review of published reports of the condition. They recently reported their findings regarding post-COVID syndrome in children in EClinical Medicine, a journal of The Lancet.
Rare hyperinflammatory post-COVID syndrome observed in children
The researchers reviewed the findings of 39 observational studies of MIS-C including 662 children between January and July 2020.
MIS-C developed between three to four weeks following SARS-CoV-2 infection. Fever (100%), abdominal pain or diarrhea (74%) and vomiting (68%) were the most common symptoms noted. Other symptoms included rash and conjunctivitis. Sixty percent of the cases had hyperinflammatory shock (very low blood pressure). Blood tests showed abnormal inflammatory, clotting, and cardiac markers.
Heart echocardiograph was performed in 90% of the children and findings were abnormal in 54% of these cases. Heart damage included dilation of the coronary blood vessels, reduced ability of the heart to pump blood, and aneurysm (localized ballooning) of coronary vessels.
Seventy-one percent of children needed treatment in the intensive care unit with 22% requiring mechanical ventilation. The average length of hospital stay was 8 days. Despite the severity of the condition most children survived after intensive treatment with immunoglobulins and glucocorticosteroids. These treatments are used in other life-threatening inflammatory conditions. A total of 11 deaths were reported (mortality rate, 1.7%). This mortality rate is higher than that reported overall for children with COVID-19 (0.09%).
Almost half of the MIS-C cases had an underlying medical condition, and half of those were overweight. A concerning finding was that children could develop MIS-C even after an asymptomatic course of COVID-19.
Heart damage is common in children with MIS-C
MIS-C is a new childhood disease thought to be linked to SARS-CoV-2, causing widespread inflammation and affecting multiple organ systems. While fortunately rare, MIS-C can occur following mild COVID-19 and is potentially lethal. However, with prompt intensive treatment most children who develop MIS-C will survive. Around half of MIS-C cases had underlying medical conditions, but it is also observed in previously healthy children.
Damage to the heart and coronary blood vessels is common, but it is not yet clear if this is permanent. “Evidence suggests that children with MIS-C have immense inflammation and potential tissue injury to the heart, and we will need to follow these children closely to understand what implications they may have in the long term,” said Dr. Alvaro Moreira, lead author of the review.
Written by Julie McShane, MA MB BS
References
1. Ahmed M, Advani S, Moreira A, et al. Multisystem inflammatory syndrome in children: A systematic review. EClinical Medicine (Lancet journal), published Sept 4, 2020. Doi: https://doi.org/10/1016/j.eclinm.2020.100527
2. University of Texas Health Science Center at San Antonio, Press release 4 Sep 2020. Post-COVID syndrome severely damages children’s hearts. https://www.eurekalert.org/pub_releases/2020-09/uoth-pss090420.php
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