75% of children with severe complications from COVID-19 were asymptomatic

75% of children with severe complications from COVID-19 were asymptomatic. A new study was conducted in the US and published in JAMA Pediatrics.

The symptoms of Multisystem Inflammatory Syndrome in Children (MIS-C) are reminiscent of Kawasaki disease - a very rare condition that causes inflammation in the walls of arteries and can obstruct blood flow to the heart.

This disease develops several weeks after infection with SARS-Cov-2. It is also characterized by severe fever, abdominal pain, red eyes, and skin rashes. In the most severe cases, young patients may require mechanical ventilation and blood pressure support.

During the study, CDC experts analyzed 1,733 out of 2,090 reported cases of multisystem inflammatory syndrome in patients aged under 20 years. Most of them (about 86%) are under 15 years old. All of them were hospitalized with characteristic symptoms 2-5 weeks after the coronavirus.

Interestingly, only a quarter of patients in this sample (24.7%) suffered from a coronavirus infection with mild symptoms, others suffered from the disease asymptomatically. However, they were all admitted to the hospital with the characteristic features of MIS-C 2-5 weeks after complete recovery.

In over 90% of children, the inflammatory syndrome manifested itself with symptoms from at least four organ systems, 58% required hospitalization in an intensive care unit. Almost a third of patients (31%) showed signs of heart failure, 51% had blood pressure dropping to a critical level. Almost every fourth victim had an excessive accumulation of fluid in the region of the heart, and 17% had symptoms of inflammation of the heart muscle (myocarditis).

The study also showed that the risk of severe complications increased from 5 years of age. 10-year-old children were significantly more likely to have heart issues, such as myocarditis and low blood pressure, compared to other age groups. At the same time, in adolescents, 14 years of age and younger, the most common symptoms were shortness of breath, chest pain, rash, and redness of the eyes. Almost two-thirds of all patients experience abdominal symptoms.

In this sample, 24 deaths were recorded. There is no information in the study on the presence of comorbidities in the deceased, but it is known that the majority of patients with MIS-C were previously completely healthy. The researchers noted that the hyperinflammatory response occurred at the time the maximum level of neutralizing antibodies was produced after infection, and it is not yet known what exactly causes it.