Genital Chlamydia trachomatis (GCT) infection is one of the most common sexually transmitted infections (STIs) worldwide. Its complications, such as pelvic inflammatory disease, tubal infertility, ectopic pregnancy, and chronic pelvic pain, pose a serious threat to reproductive health and impose significant physical, psychological, and socioeconomic burdens on infected individuals (1). However, GCT infection is often asymptomatic or presents with mild symptoms, particularly among women, allowing it to spread unnoticed and giving rise to the characteristic “silent epidemic” (2). This characteristic highlights the importance of partner notification (PN). PN is the process of identifying, notifying, and encouraging sexual partners to seek testing and treatment, and it serves as a key intervention to break the chain of transmission, prevent reinfection, and reduce complications (3–6). A health economic assessment conducted in the UK demonstrated that PN is a highly cost-effective yet underutilized infection control strategy (7).

The GCT infection has long been recognized as a considerable global public health concern. The World Health Organization estimates for 2020 indicate that roughly 129 million people aged 15–49 years were affected, accounting for nearly one-third of all new cases among the four curable STIs: chlamydia, gonorrhea, trichomoniasis, and syphilis (1). The GCT infection situation in China is similarly concerning. Since 2008, the reported incidence has increased from 32.48 per 100,000 to 55.32 per 100,000 in 2019, with the sharpest rise occurring between 2015 and 2019, when the average annual growth rate reached 10.44% (8, 9). Despite this growing burden, China has not yet developed standardized PN policies specific to GCT infection (10). In addition, empirical research on public perceptions of GCT and the factors influencing attitudes toward PN remains limited.

In recent years, Longgang District in Shenzhen, Guangdong Province, has spearheaded PN practices for GCT infection in China. This pioneering initiative not only provides valuable experience for national-scale prevention and control efforts but also highlights the urgent need for localized empirical evidence. Specifically, there is a pressing need to systematically explore the key factors that enable or hinder PN behavior within China’s unique sociocultural framework.

Currently, PN efforts have been primarily applied in the prevention and control of HIV and syphilis, whereas strategies for PN related to GCT infection remain relatively limited, particularly within the Chinese context (10, 11). PN is a multifaceted health behavior decision influenced by various factors extending beyond knowledge and attitudes to deeper individual traits and environmental resources. Hence, this study focused on sociosexual orientation and perceived social support, representing individual propensities for non-committed sexual relationships and psychosocial resources during stressful times, respectively (12–14). By examining their independent and potential interactive effects on PN attitudes in the context of GCT infection, this study aimed to clarify how these factors contribute to sexual health decision-making. Insights from this work may help inform more targeted and context-appropriate PN strategies within China’s diverse sociocultural setting.

In summary, taking Longgang District as the study object, this study aimed to systematically explore the key factors influencing attitudes toward PN of GCT infection among the general Chinese population. In particular, this study focused on the interaction between sociosexual orientation and perceived social support to address the existing gap in context-specific evidence. The study findings are expected to provide scientific support for the design of more precise and effective intervention strategies and hold important public health implications for strengthening the prevention and control of STIs.

In this study of the general population aged 18–60 years in Longgang District, when hypothetically infected with GCT, 95.83% of participants expressed a willingness to engage in PN. This proportion is remarkably high, suggesting that the public generally accepts the PN policy and that societal awareness of health responsibility and risk communication is gradually maturing. This estimate is higher than the PN willingness reported among women attending reproductive health and STI clinics in Shenzhen (87.31%) and is also at the upper end of the PN intention levels reported in some international studies (>70%) (15, 23–25). However, we note that willingness measured hypothetically may not translate into actual PN behavior. The high estimate may also reflect survey framing and anonymous online administration, which can increase socially desirable responding. In addition, Longgang District has been a pioneering area for GCT-related partner management practices, which may increase public awareness and normative endorsement of PN. Importantly, prior studies in China have reported substantially lower PN uptake when measured as actual behavior among STI patients, while higher willingness has been observed in some clinic-based samples (10, 15). Therefore, heterogeneity across studies is expected due to differences in study populations (community vs. clinic), outcome definitions (hypothetical willingness vs. actual PN uptake), and local service context. Taken together, our findings complement prior epidemiological evidence that largely focuses on clinic-based populations and observed PN uptake by providing population-based, psychosocially informed estimates of PN willingness. Nonetheless, these findings underscore the need for future studies linking these psychosocial profiles to real-world PN behaviors and partner outcomes.

Further analysis revealed that higher education levels, non-local household registration, self-rated ordinary or poor economic status, a history of STIs, higher perceived social support, and a more restricted sociosexual orientation were all significantly associated with higher PN willingness. These findings align with the core assumptions of health belief models and social cognitive theory—that health decisions are shaped by cognition, experience, and psychological traits (26, 27). Notably, this study is the first to reveal the independent and interactive effects of sociosexual orientation and perceived social support on PN willingness in the condition of hypothetical GCT infection, and the findings indicate a consistent positive additive interaction trend between the two factors, providing new insights into the social-psychological mechanisms underlying health behaviors.

Consistent with previous research, education level was found to be a crucial factor in promoting PN willingness (15, 28, 29). Individuals with higher education levels typically have better health literacy, allowing them to better understand the risks of disease transmission (30). They also tend to have stronger self-efficacy, which increases confidence in navigating sensitive communication situations (31). Furthermore, higher education enhances an individual’s social cognition and emotional regulation abilities (32), helping to reduce feelings of shame and self-blame associated with STIs, and thereby making them more likely to engage in responsible PN behaviors.

An intriguing finding of this study is that participants with local household registration and higher economic status showed lower PN willingness. We speculate that this group of individuals might possess more intimate social connections locally and may be more concerned about their own social reputation in the community (33, 34). Therefore, they may be more sensitive to the stigma and privacy risks associated with GCT infection. They may be worried about losing “face” or damaging their social image, thus leading to psychological withdrawal (35). This finding is in sharp contrast to two other studies based on patients in STI clinics, which found that the higher the economic level, the stronger the willingness for PN (15, 36). This discrepancy may be attributed to differences in the populations studied: clinic patients may have a stronger sense of health threat, while the general population in this study may be more concerned about maintaining their social image. Additionally, individuals with a history of STIs were more willing to notify their partners, which may reflect their heightened risk awareness and increased self-efficacy after experiencing infection, further demonstrating the role of experiential learning in health decision-making.

This study utilized the standardized PSSS to objectively and systematically evaluate the facilitating effect of social support on PN willingness, confirming the critical role of social support—as a modifiable external resource—in promoting sexual health. Although some previous studies did not utilize standardized measurement tools, their conclusions similarly indicated a positive association between social support and PN willingness (6, 13, 37), collectively reinforcing the universal importance of social support in enhancing willingness to engage in PN.

This study used the well-established SOI-R to assess participants’ tendencies toward non-committed relationships. The results showed that individuals with a more restricted sociosexual orientation had a higher willingness to engage in PN. This finding may reflect a stronger sense of responsibility and risk awareness in sexual health decision-making among this group. This result is consistent with multiple lines of indirect evidence: previous studies have shown that individuals with more casual sexual relationships or multiple sexual partners usually have a lower likelihood of engaging in PN (24, 27, 38, 39). Furthermore, groups with more unrestricted sociosexual orientations often exhibit higher rates of STIs and higher incidences of high-risk sexual behaviors (40–44). These findings suggest that sociosexual orientation may influence individual health awareness, which, in turn, affects health behaviors and outcomes. This phenomenon highlights the importance of considering individual sociosexual orientation differences when designing sexual health promotion and intervention strategies.

The interaction analysis in this study suggested a positive joint effect of sociosexual orientation and perceived social support on willingness to engage in PN. Although the multiplicative interaction between sociosexual orientation and perceived social support did not reach statistical significance, consistently positive additive interaction indices (RERI, AP, and SI) suggest that their joint effect on PN willingness may exceed the sum of their individual effects. Given the public health relevance of additive interactions for identifying priority subgroups (22), these findings should be interpreted as suggestive rather than definitive evidence of a positive additive interaction. From a public health perspective, this interaction pattern supports an “individual traits + psychosocial resources” framework for understanding PN behaviors and suggests the need for a stratified, stepped-support approach to PN implementation. For individuals reporting lower perceived support—particularly those with more unrestricted sociosexual orientations, who may face higher partner turnover and greater disclosure concerns—PN services could prioritize privacy-preserving, low-burden options such as provider-assisted notification, anonymous/digital notification tools, and standardized message templates. In contrast, among individuals with a more restricted sociosexual orientation, strengthening psychosocial resources (e.g., brief counseling, peer/family support, and stigma-reduction messaging) may further increase PN acceptance and follow-through. Programmatically, brief screening of perceived support and anticipated communication barriers at diagnosis could help match clients to appropriate PN options and allocate counseling and partner services more efficiently. At the policy level, these findings support the integration of psychosocial screening and tiered PN options (self-notification, provider-assisted notification, and digital/anonymous notification) into routine chlamydia case management, alongside confidentiality safeguards and staff training to promote stigma-sensitive partner communication.

This study has several strengths. First, the use of a large-scale community sample and a multistage random sampling design ensured the representativeness and reliability of the results. Second, the core variables were measured using internationally recognized standardized scales (SOI-R and PSSS), ensuring the scientific rigor and comparability of the data. Third, this study is the first to provide population-based evidence suggestive of a positive additive interaction between sociosexual orientation and social support in a community-based sample from Shenzhen (Longgang District), broadening the theoretical perspective in sexual health behavior research. Finally, this study focused on general community residents rather than clinical or high-risk groups, filling a gap in our understanding of PN attitudes related to GCT infection among ordinary residents in China. Accordingly, the findings provide practical insights for public health interventions.

However, there are certain limitations of this study that should be acknowledged. Firstly, the cross-sectional design of this study limits causal inferences. However, given the scarcity of population-based evidence related to PN attitudes toward GCT infection in China, this study was intentionally designed as an exploratory investigation to identify key psychosocial correlates and potential interaction patterns. Accordingly, these findings should be interpreted as hypothesis-generating, providing a foundation for future longitudinal and interventional studies aimed at causal validation.

Secondly, PN willingness was assessed using a hypothetical scenario rather than observed behavior and may, therefore, be overestimated due to social desirability and the intention–behavior gap. In real-world settings, PN can be constrained by stigma, privacy concerns, and relationship factors (6); accordingly, reported willingness should be interpreted cautiously and not conflated with actual PN uptake.

Thirdly, the study sample was primarily drawn from the population of urban residents in Longgang District, a highly urbanized and economically developed area in Shenzhen, China. This population is characterized by a substantial migrant population and relatively good access to STI-related public health services (45). In the Chinese context, pronounced urban–rural disparities persist in terms of health literacy, availability of sexual health services, and implementation capacity of STI prevention programs (46, 47). Moreover, sociocultural factors such as collectivist norms, concerns about “face” (mianzi), family reputation, and stigma surrounding STIs may shape partner communication and disclosure decisions differently across regions (48–50). Perceptions and expectations regarding communication about sexual health issues, stigma levels, and anticipated social consequences of disclosure may, therefore, differ substantially in rural areas or less-developed regions with distinct sociocultural contexts and healthcare infrastructures. Thus, caution is warranted when extrapolating our estimates—particularly the high PN willingness observed—to settings characterized by lower health literacy, more limited service availability, weaker local STI management systems, or stronger community-level stigma. Future research should adopt multi-site designs across diverse regions of China, including rural and under-resourced areas, to assess the robustness and contextual variability of these psychosocial associations.

Finally, although multiple covariates were adjusted for in the analysis, unmeasured factors such as sexual health knowledge and access to medical services may still have contributed to residual confounding. In addition, the binary measurement of PN willingness may not have captured the intensity of willingness or underlying psychological processes. Future studies should consider incorporating more granular outcome measures (e.g., Likert-scale assessments), collecting behavioral PN outcomes (e.g., verified partner contact, testing uptake, or treatment), and adopting sensitivity analyses or longitudinal designs to better capture real-world PN implementation and further validate these findings. In addition, the very high prevalence of PN willingness observed in this study may introduce a ceiling effect and potentially amplify ORs; therefore, alternative modeling approaches estimating risk ratios or marginal effects may be considered in future research.

In this community-based sample from Longgang District, Shenzhen, hypothetical willingness to engage in PN for GCT infection was high. Multivariate analysis demonstrated that higher education levels, non-local household registration, self-rated average or poor economic status, a history of STIs, higher social support, and a more restricted sociosexual orientation were significantly associated with higher PN willingness. A positive additive interaction was observed between sociosexual orientation and social support. Specifically, in situations with higher social support, individuals with a restricted sociosexual orientation tended to show a stronger willingness to engage in PN. These findings emphasize the critical role of socio-psychological factors in health communication behaviors and provide important theoretical and practical references for PN intervention strategies and sexual health promotion.