To investigate the characteristics of the molecular transmission network among newly reported human immunodeficiency virus type 1 (HIV-1) cases in Qingbaijiang District of Chengdu from 2022 to 2024, and to provide guidance for local HIV/AIDS prevention and control.

A total of 283 anticoagulated blood samples and demographic information from newly reported HIV-1 cases in Qingbaijiang District from 2022 to 2024 were collected. The HIV-1 pol region gene sequences were amplified by reverse transcription polymerase chain reaction (PCR) and nested PCR, followed by sequencing. A molecular network was constructed based on a genetic distance threshold of 1.5%. The patterns of the molecular transmission network were analyzed, and binary logistic regression was used to analyze factors influencing entry into the network.

A total of 277 valid sequences were obtained. Nine genetic subtypes were identified, with CRF07_BC (197 cases, 71.11%) and CRF01_AE (63 cases, 22.74%) being predominant. Under a genetic distance threshold of 1.5%, the network entry rate was 50.18% (139/277), forming 33 molecular clusters, with the number of cases in each cluster ranging from 2 to 16. Multivariable logistic regression analysis indicated that individuals aged ≥50 years (OR=44.138, 95% CI: 4.474-435.459), and those infected with CRF01_AE (OR=10.434, 95% CI: 1.981-54.966) or CRF07_BC (OR=10.371, 95% CI: 2.078-51.760) subtypes were more likely to be included in the network (P<0.05). High-risk infected individuals (degree ≥4) exhibited significant differences across various occupations, education levels, genetic subtypes, and current residences (P<0.05), and those residing in FH Town (OR=44.138, 95% CI: 4.474-435.459) had a significantly higher risk.

Among newly reported HIV-1 infections in Qingbaijiang District, the predominant genetic subtypes were CRF07_BC and CRF01_AE. Individuals infected with CRF01_AE or CRF07_BC subtypes and aged ≥50 years were more likely to enter the molecular transmission network. Certain townships showed a higher transmission risk among infected individuals. Therefore, it is recommended to establish a molecular transmission network for long-term surveillance in the region and implement targeted interventions in key towns/streets and among high-risk populations to curb the spread of the HIV/AIDS epidemic.