A rare COVID-19 complication that was originally found only in children is starting to be seen in adults. 

It is called "multi-system inflammatory syndrome in adults (MIS-A)" when seen in adults and "multi-system inflammatory syndrome in children (MIS-C)" when seen in children. 

Dr. Alisa Femia told NBC News that when she was looking at a patient's chart, it included several photos of rashes, which is often the sign of multi-system inflammatory syndrome.

According to NBC News, children were developing dangerous inflammation around the heart and other organs. 

As of October 1, the CDC reported 1,027 cases of MIS-C. Twenty of the children died.