[Study on drug resistance among newly reported HIV-1-infected individuals in Huai'an City from 2021 to 2023 based on molecular transmission networks].

To analyze the subtypes, epidemiological characteristics, and drug resistance of HIV-1 strains among newly diagnosed HIV-1-infected individuals in Huai'an City from 2021 to 2023 based on molecular transmission networks. The in-house assay was used to amplify the pol gene fragment of the virus and complete sequencing, genotyping, and analysis of drug resistance mutations. The HIV-1 molecular transmission network was constructed, and the multivariate logistic regression was used to analyze the association between demographic and sociological characteristics and network-clustering transmission. The majority of 422 infected individuals was males (84.60%), aged over 50 years (38.86%), married (48.10%), those with a junior high school education or below (59.48%), non-students (94.79%), and infected through men who have sex with men (MSM) transmission routes (54.50%). The predominant HIV-1 subtypes were CRF07_BC (33.41%, 141/422) and CRF01_AE (28.20%, 119/422). The network entry rate was 34.36% (145/422), and three active transmission clusters were identified. The multivariate logistic regression revealed that females (OR=2.256, 95%CI:1.321-3.853), those aged ≥50 years (OR=1.812, 95%CI:1.133-2.899), and those with the education level of junior high school or below (OR=2.250, 95%CI:1.306-3.900) were independent risk factors for entering the molecular transmission network. Nineteen drug-resistant cases were detected among network participants and distributed across 12 transmission clusters, of which 8 drug-resistant clusters had cross-district transmission characteristics. In summary, the 422 newly reported HIV-1 infections in Huai'an City from 2021 to 2023 are mainly transmitted by middle-aged and elderly males with low education levels and through MSM as the major transmission route. The strains are mainly CRF07_BC and CRF01_AE, and gender, age, and educational level are risk factors affecting the entry of infected individuals into the molecular transmission network. Some transmission clusters exhibit drug resistance and cross-district characteristics.