New York City Mayor Bill de Blasio said on Sunday that the city will be sending out safety guidance to parents regarding an inflammatory illness with suspected links to the coronavirus that has been detected in dozens of children. The mayor said roughly one million parents of children in the city’s public school system will receive alerts with information about the disease. They will also be advised to take their children to the hospital if they begin to exhibit symptoms, de Blasio added.

At least 38 children have been diagnosed with “pediatric multi-system inflammatory syndrome,” which has symptoms consistent with Kawasaki disease, including skin flare-ups, high fever, rash, and swollen arteries.

“There is a rare condition which we’re seeing more of just in the last days and it is causing tremendous concern,” de Blasio said at a press conference. “Our health leadership is deeply concerned.” The mayor said that 47 percent of children with the illness tested positive for the coronavirus, while 81 percent had its antibodies. De Blasio said the syndrome afflicts an “intensive, almost overwhelming immune system response that actually causes harm to the body.”