The goal of this observational study is to expound the population and characteristics of pathogenic microorganisms with co-infection, draw the pedigree of pathogenic microorganisms, and evaluate its influence on disease outcome in patients with severe hepatitis (liver failure). The main questions it aims to answer are:

• Mapping of infectious agents in patients with severe hepatitis (liver failure)
• Constructing early warning predictive models to explore how to give an individualized regimen of integrated immune function.

Liver failure is a clinical syndrome caused by a large number of necrotic hepatocytes leading to severe liver function damage, with jaundice, coagulation dysfunction and hepatic encephalopathy as the main manifestations, which can be caused by a variety of reasons, and the liver failure caused by Hepatitis B Virus (HBV) is the first one in our country, which accounts for about 80% of the cases. Through the "Eleventh Five-Year Plan" to "Thirteenth Five-Year Plan" national scientific and technological major special projects, the death rate of patients with early and middle stage of severe hepatitis B has been significantly reduced, but the death rate of patients with advanced stage is still as high as about 60%, especially when liver failure is combined with other complications, such as This study focuses on the impact of secondary infections on the clinical prognosis of severe hepatitis (liver failure), and intends to establish a prospective, multi-center clinical cohort of secondary infections in liver failure, map the infectious pathogens, correlate the basic immune status with the characteristics of the pathogen profile of the secondary infections, and establish a monitoring and early-warning system of secondary infections, so as to explore safe and effective treatment modalities. To further reduce the mortality rate of liver failure.

Inclusion Criteria:

1. Patients agreed to participate in the study and signed an informed consent form;
2. Sex is not limited and age is 18-70 years old;
3. HBsAg positive for more than 6 months, or hepatitis E IgM positive, or hepatitis E RNA positive;
4. Progressive deepening of jaundice in a short period of time (serum total bilirubin greater than 10 times the upper limit of normal or rising ≥17.1 umol/L per day);
5. Sgnificant bleeding tendency with PTA ≤ 40% and exclusion of other non-hepatic factors.

Exclusion Criteria:

1. Patients with severe hepatitis caused by other non-hepatophilic viral infections;
2. Patients who were considered by the investigator to be unsuitable for participation in the study.

Patients with severe viral hepatitis (liver failure) who met the inclusion and exclusion criteria and were hospitalized in the First Hospital Affiliated to Zhejiang University School of Medicine, Beijing Ditan Hospital Affiliated to Capital Medical University, Beijing You'an Hospital Affiliated to Capital Medical University, Huashan Hospital Affiliated to Fudan University, and Qilu Hospital of Shandong University.