IL1RL1 and COVID-19: Although the exact details of the interaction between IL-33 and neutrophils during the progression of COVID-19 are yet to be fully elucidated, we propose that the IL-33/ST2/ROS/NET pathway is an important basis for further in-depth studies that will provide a comprehensive understanding of the pathogenesis of COVID-19 and highlight the checkpoint molecules on this pathway that may yield novel strategies for the prevention and treatment of patients with COVID-19 (Figure 2).