Lack of funding

In severe infective patients who survive the initial inflammatory storm, the immune response often evolves toward a state of immunosuppression, which contributes to increased mortality and severe secondary hospital-acquired infections. However, the role of IL-6 and its receptor antagonists in patients with severe sepsis and septic shock is discussed controversially. To date, the efficacy and safety of IL-6 and its receptor antagonists in children with severe infection is not fully evaluated.

The investigators intend to enroll all children who were hospitalized in pediatric intensive care unit of Children's Hospital of Fudan University from January 2022 to December 2023. Children with a PICU length of day less than 48h will be excluded. Patients who met the inclusion criteria will be divided into trial group and control group. Clinical and demographic data, as well as treatment outcome will be collected from the electronic health record.

Inclusion Criteria:

• 1.Children between 29 days and 18 years old. 2.Severe pneumonia and/or sepsis.Patients were included who meet the guideline for diagnosis and treatment of community-acquired pneumonia in Children (2019) issued by the National Health Commission of the people's Republic of China and/or who meet the International Guide to the 2020 campaign to Save sepsis: management of septic shock and sepsis-related organ dysfunction in children.

Exclusion Criteria:

• 1.notifiable infectious diseases. 2.The researcher believes that he is not suitable to participate in other situations in this study. 3.Participants in other clinical trials in the same period. 4. discharge within 48 hours.

All children hospitalized in pediatric intensive care unit (PICU) of Children's Hospital of Fudan University from January 2022 to December 2023