In April, the emergency department of Renji Hospital East Campus, affiliated with Shanghai Jiao Tong University School of Medicine, was flooded with 200 to 300 patients every day. On one particular day, 114 ambulances arrived — more than twice the usual number. This was an unprecedented moment for Renji East Campus' emergency department. In the past, the number of patients, medical institutions, and ambulances in Shanghai had always been in a delicate balance. However, as more and more hospitals were converted into designated COVID hospitals, the pressure on the emergency departments of non-designated hospitals suddenly increased sharply.