On January 23, due to the deterioration of his condition, he went to the People's Hospital of Jialing District. The doctor diagnosed a suspected novel coronavirus infection and asked for isolation and treatment. However, Sun quietly left the hospital, and took a bus home. He was then forced to be isolated for treatment, and was diagnosed with new coronary pneumonia. Sun contacted a large number of people within a few days, leading to the quarantining of dozens of people who were in close contact with him. On 12 February, in the afternoon, a 21-year-old male assistant policeman from the traffic police brigade of the Chongzhou Public Security Bureau refused to cooperate with the community epidemic prevention volunteers for identity registration and came into conflict with them when he passed the Qingshiqiao community epidemic detection point in Changzhen Town, Longxing Town, Chongzhou City. He was eventually dismissed.