Witness Katrice Hardaway recorded the exchange on her cellphone. The man who confronted the nurse is heard shouting at him about health care workers and blaming them for the pandemic.
The nurse supposedly tried to convince the man to leave him alone, with witness Hardaway hitting the panic button on the train as the situation grew more severe.
The nurse then stood to defend himself, and the two men struggled against each other for a time.
Other passengers tried to intervene in the confrontation but when the train arrived at a stop, the instigator refused to get off. Instead, the nurse departed -- with Hardaway following him.
“Fighting through this pandemic for us, and he shouldn’t have to go through that on his way to work,” Hardaway told Chicago's WBBM-TV.
The nurse is reportedly looking to press charges; the suspect remained at large.