The studies, published in the New England Journal of Medicine, describe children who develop severe inflammation a few weeks after having had Covid-19. The inflammation often attacks multiple organ systems. In one of the studies, led by researchers at Boston Children’s Hospital, 80% of the children who developed the condition required intensive care, 20% required mechanical ventilation, and four children, or 2%, died. In the second study, from researchers from New York state, two children died.
In both studies, many of the children developed cardiovascular problems and gastrointestinal problems.
“Ours were really sick kids,” said Adrienne Randolph, an ICU physician at Boston Children’s Hospital and senior author on one of the papers. She said, though, that it’s believed the condition is rare. Her team’s paper reported on 186 children with the condition who were reported by doctors from 26 states.
An editorial written by Michael Levin, from the department of infectious diseases at Imperial College London, said there have been roughly 1,000 pediatric cases of the condition reported worldwide to date. He suggested more are likely being missed, because case definitions require evidence of prior Covid-19 infection, which may have been missed in some mild cases. Children are much more likely than adults to be symptom-free or have only mild symptoms when they contract Covid-19.
“There is concern that children meeting current diagnostic criteria for MIS-C are the ‘tip of the iceberg,’ and a bigger problem may be lurking below the waterline,” Levin wrote.
He suggested MIS-C occurs in two of every 100,000 people under the 21 years of age who contract SARS-CoV-2 virus, which causes Covid-19. The infection rate in people under the age of 21 years was 322 in 100,000 over the course of the period studied.
Randolph said the average age of the children affected was about 8 years old. Research is underway to try to determine what the long-term consequences for children who develop MIS-C are, she said.
This is a breaking news story and will be updated.