Taking the first deep dive into how the immune system is behaving in patients with multisystem inflammatory syndrome in children (MIS-C), researchers at Children’s Hospital of Philadelphia (CHOP) and the Perelman School of Medicine at the University of Pennsylvania have found that children with this condition have highly activated immune systems that, in many ways, are more similar to those of adults with severe COVID-19. The results, published today in Science Immunology, show that better understanding the immune activation in patients with MIS-C could not only help better treat those patients but also improve treatment for adults with severe COVID-19.