Trends in sexually transmitted and blood-borne infections in China from 2005 to 2021: a joinpoint regression model

This study showed that the overall diagnosis rate of all five STBBIs were on the rise in China from 2005 to 2021, although the rate of increase appears to be slowing. The overall diagnosis rate increased rapidly from 2005–2007 but leveled off after 2007. This suggests that although the prevention and control of STBBIs in China has made certain achievements in recent years, it remained an important public health challenge in China.

Several main factors may explain the increase in overall STBBI diagnosis rate during 2005–2019. First, the rapid economic and technological development in the country, together with the popularity of social media, have facilitated sexual encounters and a more open attitude towards sexuality in general, leading to increases in diagnosis rate of AIDS and gonorrhea [24]. Additionally, a series of studies in China have shown that most people, including college students, young men and men who have sex with men face many barriers to condom use and PrEP [25,26,27]. Another factor is the growing prevalence of STBBI screening.

The slowing down in the increase in STBBI diagnosis rate during 2019–2021 may be due, in part, to the COVID-19 pandemic. On the one hand, government efforts to limit the spread of the causative virus led to partial and total city lockdowns, restrictions on gathering and socializing, as well as traffic restrictions [28]. All these made sexual encounters more difficult. On the other hand, the observed decreases in annual newly diagnosed cases of STBBIs during the COVID-19 pandemic might also be attributed to reduced availability of diagnostic testing as individuals faced challenges accessing routine sexual healthcare and testing due to citywide lockdowns and travel restrictions. Indeed, diagnosis rate of the five STBBIs also declined in 2019–2021 [29], consistent with our observations.

Among the five STBBIs explored in this study, numbers of infections of hepatitis B and gonorrhea declined during the study period. Among these two, hepatitis B showed the highest diagnosis rate, which reflects the relatively high prevalence of this virus in China and widespread screening for it [30]. Indeed, the rapid increase in the diagnosis rate from 2005 to 2007 might be due to direct reporting of cases into a national infectious disease surveillance system since 2004 [31]. However, the diagnosis rate of hepatitis B declined faster than that of infection of the other four pathogens, possibly due to increasingly comprehensive strategies adopted by the Chinese government to prevent the spread of hepatitis B. In 2002, China incorporated the hepatitis B vaccine into the panel of required immunizations, resulting in an increase in hepatitis B vaccination rates [8]. Since 2008, hepatitis B has joined tuberculosis and HIV as three infectious diseases against which the Chinese government has prioritized its prevention and control efforts. In parallel, publicity campaigns have been launched and the healthcare sector has implemented comprehensive prevention and control programs, including measures to promote safe injection practices as well as systematic screening of blood donations [32].

These efforts, while effective, still have a long way to go, given that hepatitis B accounted for the greatest number and proportion of STBBIs during our 17-year study period. Indeed, one third of the 240 million people living with chronic hepatitis B worldwide reside in China [33, 34]. The diagnosis rate of hepatitis B has remained relatively constant since 2014, which is consistent with the findings of Zhang MY’s study [20]. One reason may be that a large decrease as a result of widespread vaccination has already occurred and cannot be expected in the future. Another may be that government-funded programs offering free vaccination and testing services have operated in isolation from each other, preventing concerted efforts to control hepatitis B [35]. Better coordination of prevention efforts at the national level may further reduce the diagnosis rate of hepatitis B.

Gonorrhea diagnosis rate steadily decreased until 2011, at which point it slowly started to rise again. This trend is consistent with the findings of Wang YJ’s study [18]. This could be attributed to multiple factors, including drug resistance acquired by Neisseria gonorrhea [36], increased national surveillance of sexually transmitted infections, more proactive testing, an increase in the number of people engaging in condomless sex, particularly male same-sex sexual behaviors as well as sex between female sex workers and their clients [37]. Policies to prevent gonorrhea may wish to take into account that incidence is higher in areas with high per capita gross domestic product, transient populations, inadequate health care, higher male–female ratio and high divorce rates [38].

The increase in diagnosis rate of HIV and syphilis during the study period may reflect an increase in sexual behavior, especially as people make use of social media to search for sexual partners [24]. HIV prevalence showed two inflection points in 2010 and 2013, and the rapid increase from 2010 to 2013 may be related not only to a large increase in infections among men having condomless male same-sex sexual behaviors, but also to increased rates of screening and detection among this group [39, 40]. Another potential explanation is the migration of people from high HIV-prone areas to big cities in order to achieve better living conditions and employment opportunities, which may have expanded the HIV epidemic [41].

Inflection points for syphilis diagnosis rate were detected in 2010 and 2019. From 2005 to 2010, the rapid increase in syphilis diagnosis rate could be accounted for by the considerable increase in congenital syphilis. Prior to 2010, health care efforts to prevent mother-to-child transmission focused on the prevention and control of HIV, and syphilis was not prioritized, possibly contributing to its inadequate prevention and control [42]. Syphilis can be co-transmitted with HIV, which may explain the observed rise in diagnosis rates of both types of infection [37]. In fact, the increased prevalence of co-screening for HIV and syphilis has led to higher detection of latent syphilis [43]. From 2010 to 2019, the rise in syphilis diagnosis rate slowed, which is similar to the findings of Ma N’s study [19], and could possibly reflect new government policies [44, 45] to prevent and control syphilis, particularly mother-to-child transmission, in parallel with efforts to reduce vertical transmission of HIV and hepatitis B.

The diagnosis rate of hepatitis C showed an upward trend throughout the study period, but this leveled off after 2012, which is similar to the findings of Zhang MY’s study [20]. This may reflect growing awareness of prevention, diagnosis, and treatment of hepatitis C among health professionals following the 2012 publication of the APASL Consensus Statements and Management Algorithms for Hepatitis C Virus Infection [46]. After 2019, the diagnosis rate of hepatitis C declined slightly, and this inflection point coincided with an inflection in the diagnosis rate of syphilis. It may be that the same government measures against COVID-19 reduced diagnosis rates of both types of infection. Another factor may be the release of a slate of government guidelines on how to screen vulnerable populations for hepatitis C and how to treat infection effectively [12, 47].

Our analysis leads to the following recommendations for future prevention and control of STBBIs in China. The general population should be educated about STBBIs, and anti-STBBI interventions should focus on vulnerable populations. Routine immunization and vaccination against hepatitis B should be expanded to all adults [48, 49]. Since syphilis and HIV share similar transmission routes and risk behaviors, prevention and control measures for both diseases should be tightly coordinated [37], mainly through screening of target populations and timely treatment of infected cases to curb transmission [50]. Strategies to reduce diagnosis rate of gonorrhea should focus on increasing condom accessibility to vulnerable populations, especially migrant workers and divorcees [38], and on developing alternative therapies to compensate for antibiotic resistance and lack of next-generation antibiotics in the pipeline [36]. Hepatitis C may be reduced through enhanced screening, strict screening of blood donors, prevention of sexual transmission and careful monitoring of potential mother-to-child transmission [35]. Additionally, measures to provide disposable needles and methadone substitution treatment for people who inject drugs should be continued, since needle sharing for drug use is the main transmission route of hepatitis C virus in China [51]. The eradication of STBBIs requires not only awareness and adoption of protective behaviors, but also the collaborative efforts of all sectors of society because STBBIs are closely related to socioeconomics. Finally, our analysis highlights the usefulness of regular assessments of trends in STBBIs in order to allow timely adjustment of strategies to maximize efficacy.

To our knowledge, this study is the first to use joinpoint regression models to evaluate the overall trends in STBBIs in China from 2005–2021. While the findings are of immediate relevance to researchers and policymakers, they should be interpreted carefully in light of some limitations. First, our data came from Chinese CDC reports, and a potential limitation of this study could be the impact on STBBIs trends due to changes in reporting practices and guidelines, as well as possible underreporting. Moreover, there were disparities in the STBBIs data between the CDC sources and the GBD and WHO sources. This disparity could potentially lead to inconsistent outcomes when comparing this study to those employing GBD and WHO sources. Nevertheless, we maintain faith in the Chinese CDC data’s credibility as the most authoritative source in China, offering valuable insights for developing relevant policies and conducting research on STBBIs. Second, our study design is not causal inference, limiting the ability to determine which factors have caused the observed trends in STBBIs. Therefore, while this study discussed some possible factors for the trends in STBBIs, further research is needed to establish causal relationships. Third, our analysis was based on national STBBI data, which could be repeated in the future using province-level data to examine STBBI trends at greater resolution. Finally, we lacked data on STBBI diagnosis rate by age group, and were unable to standardize diagnosis rate.