cytokine

The serious inflammatory syndrome sending some children and teens to the hospital remains extremely uncommon, doctors say. But if your child spikes a high, persistent fever, and has severe abdominal pain with vomiting that doesn't make them feel better, call your doctor as a precaution. Sally Anscombe/Getty Images hide caption

Health care workers assist a COVID-19 patient in Spain. Some evidence from Europe and China suggests an overzealous immune response may be contributing to the severe illness in some patients. Felipe Dana/AP hide caption