Our study reported the HIV epidemiology over the last decade in Nanjing. The HIV prevalence showed an increasing trend and reached to 0.057% by 2020. It is lower than the national average level (0.09%) reported in 2018. Due to the introduction of HAART from 2005 in Nanjing [19, 20], PLHIV who accepted ART have good virological and immunological responses and this has resulted in improvements of their life expectancy [21, 22]. A region’s HIV epidemic inflects the disease burden and determines the amount of medical resources the local government . HIV prevalence in Nanjing showed a steadily increasing trend; considerable efforts including patient care, ART service promotion, discrimination elimination and input of medical resources should be strengthened.
The proportion of Youth PLHIV increased initially (2011–2016), and stabilized during the later period (2017–2020), which was consistent with the trend of the national epidemiological characteristics of Youth aged 15–24 years . The Youth face a higher risk of HIV infection due to their increased sexual activity and related risky behaviors [24, 25]. Although we observed the proportion of male PLHIV was much larger than female among three age groups, male Youth was the highest-risk group compared with that among Middle-aged and Elderly. The reason may lay in the transmission mode with almost ninety percent infections among Youth being attributed to homosexual transmission, it is consistent with other studies that the new HIV infection rate among Youth MSM (15–24 years old) is at a high level in China [26, 27].
It is encouraging that almost ninety percent Youth PLHIV in Nanjing were diagnosed with HIV stage. On one side, the Youth were well educated and active to search HIV/AIDS health education knowledge and access to counseling and testing services. On the other side, several interventions, including expanding the publicity of HIV/AIDS related knowledge, sex and reproductive health education, making HIV testing more accessible, offering adolescent and college student peer education programmes, have been taken to combat against the HIV epidemic in Nanjing during the decade.
Consistent with other reports in China, the rapid rising of newly identified PLHIV among Elderly in Nanjing has caused growing concerns . The proportion of Elderly ncreased almost twice (12.8–24.6%) with fluctuations over the decade. Li Chen reported previously that elderly men, with monotonous and lonely spiritual life, have more complex and diverse sexual needs than Youth. They have less knowledge about HIV/AIDS, and are prone to take commercial or high-risk sexual behaviors . Meanwhile, they are less likely to use condoms during sex behavior, which puts them at greater risk of infecting HIV . Furthermore, they may transmit HIV to their spouses, non-commercials or commercial sex partners , which is the reason for the proportion of female in Elderly was higher (13.7%) than that in Youth (3.7%) and Middle-aged (8.2%).
Moreover, the biggest challenge for Elderly PLHIV was late diagnosis. Over one third of them were already at AIDS stages when they were diagnosed. Late diagnosis may lead to grave consequences both for individuals and the society, such as increased mortality, development of opportunistic infection , high healthcare costs , and increased transmission because of unawareness of infection status .
The maps of the HIV prevalence showed the increasing epidemic over this decade. The rising accumulative HIV prevalence posed the challenges to manage the burden of PLHIV care, follow-up and management. Peng et al previously analyzed the spatial clustering of PLHIV in Jiangsu Province, they considered that the clustering of HIV infection indicated certain predisposing factors and geographical characteristics in the region, which lead to the HIV/AIDS epidemic . Our spatial scanning results showed the tendency of clustering of relatively high prevalence districts and urban districts. The spatial clustering at district level of HIV prevalence among Middle-aged was shrinking, and that of Elderly remained unchanged, while that of Youth is expanding.
We found that by the end of 2020, both urban districts Gulou and Qinhuai were the clustering regions among three age groups. Gulou is always the economic center of Nanjing, in which medical institutions are well resourced, and the population is relatively dense; in addition, Gulou has some special venues, like Gulou park and Xiuqiu park, where MSM like to gathered and active. For Qinhuai, it has more famous settings well-known by MSM, like gay baths, bars and teahouses . Furthermore, Qinhuai has prosperous commercial sex exchange in ancient times. Although the exchange of sexual services is now illegal, some commercial sex behaviors still take place through sneaky ways.
Except for Gulou and Qinhuai, urban districts like Xuanwu, Jianye and Yuhuatai districts also exhibited HIV prevalence clustering among Middle-aged. These three districts, with their developed economy and large population flow, are prone to attract many foreign infection sources, leading to relatively large-scale epidemics. Among Youth, two additional clustering districts, Qixia and Jiangbeinewarea, have been added to the clustering list. The reason may be that there are many universities and colleges in these two districts, and the student epidemic fostered Youth HIV clustering [36, 37]. The clustering districts among Elderly were relatively stable locating at four districts, that is, Gulou, Qinhuai, Xuanwu and Qixia. These four districts’ medical resources accounted for over 70% of whole Nanjing. Due to the late diagnosis of Elderly, the regional clustering was more a reflection of medical resources and the mobilization of detection.
There are some limitations in our study. Firstly, our analysis strictly based on national case reporting system, which is sensitive to testing policy and the distribution of medical recourses. Therefore, PLHIV who had not yet been diagnosed were not included. Secondly, we did not analyze comprehensively for the contributing factors for the spatial variations in HIV cases which could enable to identify more detailed intervention targets and strategies. Thirdly, for some suburban areas, like Jiangning, Lishui and Gaochun, the clustering spatial analysis should deep on the community level.
In conclusion, the local policies for HIV prevention should consider the steadily increasing HIV prevalence, the variation of age and geographic regional distribution. Behavior interventions among Youth MSM and early diagnosis among Elderly should be strengthened. The clustering area, including urban, MSM active and university gathered districts, need more medical resource and control input.