New York City Mayor Bill de Blasio confirmed Monday that the Centers for Disease Control and Prevention has linked a troublesome new syndrome that is affecting children to COVID-19. The CDC said that multi-system inflammatory syndrome in children, or MIS-C, causes inflammation of the blood vessels and is potentially deadly.

According to PIX11, there have been at least 145 cases of MIS-C in New York. Three of the affected people, including a 5-year-old, have died.

Symptoms of the syndrome include:

• Persistent fever
• Irritability or sluggishness
• Abdominal pain, diarrhea, vomiting
• Rash
• Conjunctivitis or pink eye
• Enlarged lymph node on one side of the neck
• Red cracked lips or tongue
• Swollen hands and feet

The New York Times reports a case of a 14-year-old from Queens suffered unusual symptoms in April and ended up in urgent care, unable to move. Jack McMorrow suffered heart failure from MIS-C and said the pain was like “someone injected you with straight-up fire.” After 10 days of being hospitalized under intense scrutiny and injected with steroids, Jack recovered and was released on May 7, says the Times.

According to the Times, instead of targeting the lungs like the primary coronavirus infection does, this syndrome causes inflammation in the whole body and can cripple the heart. It erupts mainly in school-aged children, rather than infants and toddlers.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said in a Senate hearing last week:

“We’ve got to be careful [that] we are not cavalier in thinking that children are completely immune to the deleterious effects.”

Parents are urged to check with their pediatrician if their child exhibits any symptoms.