Title : Research on precise traceability and strategies of AIDS based on molecular-social networks

Objective: To construct a molecular transmission network of newly reported HIV cases in a county-level city of Chengdu from 2019 to 2021, analyze its characteristics, and identify key populations and factors driving local transmission through integrated molecular-social network analysis, thereby informing precise prevention strategies.

Methods: The study was conducted in City A, an area with a severe and rapidly growing epidemic. Basic information and blood samples were collected from newly reported individuals. Viral genes were amplified via nested PCR and sequenced to distinguish subtypes. Molecular networks were constructed using the gene distance method. A subset of individuals identified as key spreaders within the molecular network underwent social network investigation via questionnaires and in-depth interviews. Spatial analysis, χ² tests, and logistic regression were used to analyze geographical distribution and influencing factors.

Results: Among 561 obtained gene sequences, CRF01_AE (50.98%) and CRF07_BC (35.29%) were the dominant HIV-1 subtypes. A total of 290 individuals (51.69%) entered the molecular network, forming 67 clusters, including 116 high-risk disseminators and 6 dynamically expanding clusters. Spatial analysis revealed aggregated distribution, with TP Street as a significant hotspot. Individuals aged ≥50 and those with subtype B were more likely to enter the network and become high-risk spreaders. Social network tracing of 150 individuals found high-risk sexual behaviors were prevalent: 73.33% reported commercial heterosexual behavior, primarily occurring in tea shops and street-side stores, with 40% of traceable locations concentrated in TP Street. We constructed 138 ego-centric sexual networks comprising 848 members, with commercial partnerships being predominant. Through partner mobilization, 116 contacts were tested, identifying 2 new cases. The integrated molecular-social network of 236 individuals verified 31 molecularly linked transmission pairs and corrected the transmission routes for 2 cases.

Conclusions: The HIV epidemic in City A features diversified sources and ongoing localized transmission, particularly driven by commercial heterosexual networks among middle-aged and elderly men in key areas like TP Street. The integration of molecular and social network analyses proved effective in revealing transmission patterns, verifying links, and identifying core groups and locations. These findings support the establishment of a dynamic molecular network monitoring system coupled with targeted social network traceability for high-priority clusters, which is essential for designing precise, evidence-based intervention strategies.

Keywords: HIV; Molecular network; Social networks; traceability; Strategy

MD, MA, Ph.D,Professor, Vice Dean, School of Management, Chengdu University of Traditional Chinese Medicine; Postdoctoral Fellow(2014-2015), Johns Hopkins University Bloomberg School of Public Health (USA); Academic and Technical Leader of Sichuan Province; High-level Overseas Returnee Talent of Sichuan Province; Academic and Technical Leader of the Health Commission of Sichuan Province. Has led 45 research projects at various levels, including those funded by the National Natural Science Foundation of China and the Ministry of Education's Humanities and Social Sciences Program, and published 82 papers as first author or corresponding author. Possesses over 20 years of experience in HIV/AIDS-related research.