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Summary: Background: Since 1992, when recombinant hepatitis B vaccine was introduced in China, government health officials have used nationally representative serological surveys to monitor progress in prevention and control of hepatitis B. In 2020, we conducted the fourth seroepidemiological survey, which for the first time included medical evaluation of the clinical status of HBsAg positive subjects over the age of 15 and their medical management. We report survey results in comparison with the three previous surveys. Methods: Consistent with previous national surveys, the 2020 survey used a stratified, three-stage cluster random sampling method to select for evaluation 1-69-year-olds in 120 national disease surveillance points. Blood samples were tested for HBsAg, anti-HBV surface antigen (anti-HBs), and anti-HBV core antigen (anti-HBc) in the National Hepatitis Laboratory of the Institute for Viral Disease Control and Prevention of China CDC. HBsAg positive subjects aged ≥15-year were evaluated for evidence of liver disease, and through face-to-face questionnaire-based survey, we determined the healthcare management cascade of HBV-infected individuals. Findings: HBsAg prevalence in 1–69-year-olds was 5.86%; in children 1–4 years of age, seroprevalence was 0.30%; 75 million people were living with HBV nationwide. Among HBsAg-positive individuals 15 years and older, expert medical examination found that 78.03% were HBsAg carriers with no evidence of liver damage, 19.63% had chronic HBV with liver enzyme abnormalities, 0.84% had evidence of cirrhosis, and 0.15% had evidence of liver cancer. 59.78% of HBsAg + individuals were aware that they were positive before the survey, 30 million were unaware; 38.25% of those who knew they were positive (17 million) had medical indications for antiviral treatment, and 17.33% of these individuals (3 million) were being treated with antivirals. Interpretation: The decline in HBsAg prevalence in the general population, from 9.72% in 1992 to 5.86% in 2020, and in 1–4-year-olds from 9.67% in 1992 to 0.30% in 2020, shows progress that continues on track toward WHO targets for prevention of new infections. Implementation of acceptable strategies to identify infected individuals and offer long-term medical monitoring and management will be important to prevent complications from hepatitis B infection and for meeting WHO cascade-of-care targets. Funding: The study was funded by the Major Science and Technology Special Project of China’s 13th 5-Year Plan (grant no. 2017ZX10105015); Central finance-operation of public health emergency response mechanism of Chinese Center for Disease Control and Prevention (131031001000200001, 102393220020010000017).

【Objective】 Implementation of saving-water irrigation is a strategy affecting not only crop growth but also many other aspects directly or indirectly. How to comprehensively evaluate its consequence is an issue that remains largely elusive. The purpose of this paper is to fill this knowledge gap. 【Method】 A comprehensive evaluation system for water-saving irrigation projects was constructed, with its impacts on technical aspect, socioeconomic aspect, and ecological and environmental aspect taken into account. It considered irrigation precision and intelligence, economical return, and consequence for ecology and carbon; the evaluation system was built based on literature review, content analysis and knowledge management reconstruction. The precision includes effective utilization of irrigation water, irrigation uniformity and implementation of water measurement technologies; the economy includes crop yield increase, investment return, and timely payment for water bills; intelligence includes convenience of operation and management of irrigation project, as well as soil-moisture monitoring network; ecology includes vegetation coverage, soil salinization, surface water and groundwater improvement; carbon includes land and energy saving. We applied the model to three >10 000 mu (1650 acres) irrigation districts with smart irrigation system in Gansu, Ningxia and Qinghai province, respectively. 【Result】 In Qinghai province, the unattended and remote-control photovoltaic water lifting and micro-irrigation district improved photovoltaic water lifting efficiency and irrigation uniformity, thereby increasing comprehensive water efficiency by 32.8%. In Gansu province, implementation of the intelligent scheduling of canals with integrated gates for measurement and control increased the comprehensive water efficiency by 26.6% due to the improved irrigation automation, reliability of measurement, timely payment for water bills, and reduction in energy and labor. In Ningxia, the improvement in flow matching of pumping station units and extended water networking link increased its comprehensive water efficiency by 27.5% due to the enhanced water supply, water saving irrigation guarantee. 【Conclusion】 Constructing modern irrigation districts needs a comprehensive evaluation system to evaluate its impact not only on crops but also on many other aspects such as automatic monitoring of soils and crop traits, intelligent control and precise scheduling of the irrigation projects.