Early in the pandemic, some children fought off COVID with few, if any, symptoms, only to go into organ failure a few weeks later.
Most recovered after aggressive treatment, but their sudden illness, dubbed multisystem inflammatory syndrome in children (MIS-C), remained a mystery.
Now, a team of scientists from UC San Francisco, Chan Zuckerberg Biohub San Francisco, St. Jude Children's Research Hospital and Boston Children's Hospital has discovered what led to many of these cases, with a study that has implications for other autoimmune diseases.
The researchers found that the children's immune systems had latched onto a part of the coronavirus that closely resembles a protein found in the heart, lungs, kidneys, brain, skin, eyes and GI tract, and launched a catastrophic attack on their own tissues.
The study, published Aug. 7 in Nature, offers one of the clearest connections yet linking viral infection and subsequent autoimmune disease.
"Thanks to our world-class team we've found an answer for how children get this mysterious disease," said Aaron Bodansky, MD, a critical care fellow in UCSF's Department of Pediatrics and lead author of the paper. "We hope this kind of approach can help break new ground in understanding similar diseases of immune dysregulation that have stumped us for decades, like multiple sclerosis or type 1 diabetes."
COVID's unexpected consequence in kids
As the novel coronavirus spread among millions of people, MIS-C cases mounted, affecting about 1 in 2,000 children under 18 with COVID.
Adrienne Randolph, MD, MSc, a critical care pediatrician at Boston Children's Hospital and co-senior author of the paper, tracked these cases and collected patient samples through a national network of pediatric ICUs she had founded called Overcoming COVID-19.
"Every time COVID peaked in an area, about 30 days later, there'd be a peak of these kids presenting with what looked like septic shock in our network of ICUs, except they were negative for all kinds of infection," Randolph said. "If we hadn't intervened and supported them, they could have died."
