Dear Editor,rnIn China,HIV-1 CRF01_AE has always been one of the most prevalent subtypes,especially among sexually active population,since it was initially reported in Yunnan and Guangxi Provinces during the early 1990s (Cheng et al.1994;Yu et al.1998;Chen et al.1999).Multiple inde-pendent introductions of CRF01_AE have led to the establishment of at least eight epidemic lineages in China,which have been circulating among different high-risk populations and have variable prevalence and geographic distribution (Li et al.2017).Four main lineages were dominant among heterosexuals/injecting drug users (IDUs)and men who have sex with men (MSM);of these,two homosexual lineages accounted for about 60％ cases(Wang et al.2017),in line with that homosexuals are the most high-risk population in China nowadays (Dong et al.2019).Shenyang is located in Northeastern China with ＞ 8 million population and attract migrants from neighboring regions,which might directly or indirectly affect the HIV epidemic in neighboring cities,owing to the frequent population exchange.In Shenyang,multiple HIV subtypeshave co-existed and heterosexuals,IDUs,and those who received blood transfusions were identified as the main risk groups historically (1997-2004) (Han et al.2010).Pre-sently,MSM became the most high-risk group with an HIV prevalence of 10.8％ (Zhang et al.2018),and the HIV epidemic was mainly driven by two lineages of CRF01_AE among this population,accounting for ＞ 70％ of all HIV-1 infected individuals in Shenyang.The transmission dynamics of viral lineages would reveal the epidemic characteristics of HIV through time and space and could provide key information for the performed interventions such as targeting the viral sources,sinks,and hubs throughout the viral transmission chains (Vrancken et al.2020a,2020b).