Background: WHO has recommended that antiretroviral therapy be provided to all HIV patients to reduce future HIV transmission at the population level. Aside from the HPTN 071 (PopART) community based randomized trial which indicated that universal testing and treatment can reduce HIV incidence at the population level, such a public health strategy has not previously been studied in real-world settings. Methods: In this longitudinal phylogenetic-network study in Guangxi, China, the longitudinal baseline and follow-up data was collected from HIV patients in 2014 and newly diagnosed HIV patients from 2015 to 2018, respectively. We used a genetic distance threshold of 0.75% to analyze the proportions of genetic linkage between annual newly diagnosed HIV patients with HIV patients at baseline stratified by treatment. Findings: Among 804 newly diagnosed HIV patients during 2015-2018, 399 (49.6%) of them genetically linked to HIV patients at baseline during 2014-2017. The overall proportion of genetic linkage between newly diagnosed HIV patients during 2015-2018 with untreated and treated HIV patients at baseline during 2014-2017 was 6.2% and 2.9%, respectively. The prevention efficacy in HIV transmission for treated HIV patients was 53.5% (95% CI: 42.0%-65.0%). There was no significant reduction in HIV transmission among treated HIV patients on dropout or with missing viral load measures. Interpretation: Combined with the HPTN 071 (PopART) study, our study results strongly support the feasibility of treating all HIV patients for future reductions in HIV transmission at the population level in real-world settings. Comprehensive intervention prevention programs are urgently needed. Funding Statement: This study was supported by the Guangxi Science and Technology Bureau (Grant AB16380213), Guangxi Medical and Health Project (Z20170126), National Natural Science Foundation of China (Grants 11971479, 81460510 and 81360442), Guangxi Bagui Honor Scholarship, Ministry of Science and Technology of China (2018ZX10721102-006, 2018ZX10715008), and Chinese State Key Laboratory of Infectious Disease Prevention and Control. Declaration of Interests: The authors declare that they have no conflicts of interest. Ethics Approval Statement: The institutional review board (IRB) of the Guangxi CDC approved this study.
