A Molecular Epidemiological Study of HIV-1 Transmission in the Republic of Armenia

The HIV-1 epidemic in Eastern Europe and Central Asia (EECA) remains a major public health burden, but molecular epidemiological data for several countries, including the Republic of Armenia, are limited. To address this gap, we analyzed 1549 HIV-1 pol sequences from samples collected in the Republic of Armenia between 2017 and 2024, representing 29.9% of all people living with HIV in the country. Molecular networks were constructed using a genetic distance threshold of 0.015 substitutions/site, and multivariable logistic regression was performed to identify factors associated with clustering. A total of 132 molecular clusters (449 sequences, clustering rate 29.0%) were identified. Independent predictors of clustering included male-to-male sexual contact (aOR = 2.43), having a labor migrant partner living with HIV (aOR = 1.56), and residence in Yerevan (aOR = 1.40). Conversely, lower odds of clustering were associated with virus exposure in the Russian Federation (aOR = 0.47) and with age at diagnosis between 45 and 55 years (aOR = 0.49). Large clusters (≥10 individuals) were predominantly composed of young MSM residing in Yerevan (p < 0.001 for all). These findings suggest that young MSM in Yerevan play a role in local HIV transmission. At the same time, our data lead us to hypothesize that labor migrants working in the Russian Federation may act as a “bridge” between cross-border and local HIV-1 molecular networks through their sexual partners. This study provides a detailed molecular characterization of the HIV epidemic in the Republic of Armenia based on relatively high sampling density and identifies priority populations for targeted prevention efforts.