This study was conducted from January to April 2024 in Weifang High-tech Zone and Changle, representing urban and rural areas, respectively. A purposive sampling method was employed to select administrators and physicians from primary healthcare institutions participating in the VHEP (14). Administrators comprised hospital directors, department heads, and key project leaders directly involved in VHEP-related management and decision-making. Physicians included general practitioners, specialists, and public health physicians, all of whom had received formal VHEP training and had been continuously engaged in the program since its implementation, ensuring thorough familiarity with its operations. The selection of participants followed a three-stage process: First, an initial list of eligible candidates was compiled based on recommendations from health administration departments and institutional leaders. Second, stratified sampling was applied according to institution type (urban vs. rural), professional position, years of service, and specific responsibilities to ensure diversity in roles and experiences. Finally, potential interviewees were contacted via telephone or in person to explain the study aims and procedures, after which their participation was confirmed. All participants were informed about the study and provided their voluntary consent to participate. The selection process for information providers, along with data collection and analysis, was iterative. The absence of new categories emerging in three consecutive interviews was regarded as an indication of theoretical saturation (15). Ultimately, we completed a total of 31 interviews.

The interview checklist for this study was developed using a semi-structured interview guide, informed by relevant literature (16, 17). It encompassed participants’ experiences, perspectives on policy implementation, current challenges, and expectation, details were shown in Table 1. Prior to the interviews, participants were informed about the purpose and significance of the study. The location for each interview was selected based on the participants’ preferences, with the primary requirement being a quiet and private environment. All interviews were conducted in a one-on-one, face-to-face format, and the entire process was audio-recorded. Each interview lasted between 30 and 40 min. The study adhered to the principles outlined in the Declaration of Helsinki and complied with the Standards for Reporting Qualitative Research (COREQ-32) (18).

Interview data were analyzed in accordance with the coding procedures outlined by Corbin and Strauss, which consisted of three stages: (1) open coding, (2) axial coding, and (3) selective coding (19). Figure 1 presents the data collection and analysis process.

Open coding is also called initial coding. It entails disaggregating the raw interview transcripts, followed by the condensation and categorization of meaningful segments through iterative comparison, ultimately leading to the conceptualization of initial themes (20). In this study, two researchers independently reviewed all interview transcripts, highlighting statements related to VHEP and eliminating sentences that conveyed similar, identical, or ambiguous meanings. The remaining sentences were then preliminarily categorized to establish the original concepts and classification results for open coding.

Axial coding involved systematically refining, adjusting, and classifying the categories derived from open coding. This process included merging categories with shared meanings and clarifying the relationships among subcategories to establish coherent connections (21). Given the influence of human, material, and environmental factors on the implementation of health policies, the researchers integrated the initial categories, analyzed their internal connections, and extracted the main categories based on these considerations.

Selective coding was conducted to identify and articulate the core category emerging from the data. This involved systematically analyzing its relationships with other main categories, integrating these connections into a coherent narrative (“storyline”), and ultimately deriving the theoretical findings of the study (22). Guided by the theme of the VHEP, this study synthesized raw textual statements and the main categories derived from axial coding to identify a core category. Through this process, this study delineated the current implementation status, underlying causes, and potential strategies related to the policy, thereby constructing a coherent theoretical “storyline.”

Theoretical saturation refers to the point at which no additional data can be obtained to further develop the properties of a category, serving as a critical indicator of the completeness of the theoretical model (23). In this study, theoretical saturation was assessed through a combination of expert interviews and validation processes. The procedure involved two steps: (a) Three experts in the relevant field were interviewed, and their responses were transcribed and analyzed through coding. The analysis indicated that no new codes emerged beyond those identified in previous coding rounds. (b) The research data, coding results, and their alignment with the CFIR framework were subsequently submitted to experts for review. Consensus among the experts confirmed that the theoretical model had achieved data saturation.

To meet the rigor requirements of qualitative research, this study controlled for potential influences stemming from the backgrounds and perspectives of the research team on the study. The team consisted of three experts: two senior public health researchers specializing in vaccine policy and one master’s-level researcher focused on health services research and implementation science. All members possessed experience with qualitative methods and were well-acquainted with China’s primary healthcare context. This background facilitated a nuanced understanding of policy implementation and system-level barriers; however, it also introduced potential biases, particularly concerning structural and administrative challenges. To mitigate such biases, we maintained reflective logs throughout data collection and analysis to document and delineate our preconceptions. Furthermore, data coding was conducted independently by two researchers, with discrepancies discussed and resolved through consensus and regular consultations with an external qualitative methods expert. To enhance the credibility of these findings, the summary of the results was shared with selected participants for verification. Following the completion of the grounded theory analysis, the Consolidated Framework for Implementation Research (CFIR) was used as a post-hoc sensitizing and interpretive lens (24). The Consolidated Framework for Implementation Research (CFIR) is used to assess the diverse factors influencing the implementation of complex health interventions. Previous studies have demonstrated its strong applicability in policy implementation research, as well as its capacity to systematically categorize barriers and facilitators (25).

This research obtained ethical approval from the Ethics Committee of the Weifang Center for Disease Control and Prevention (ID: 2024-003). Respondents were provided with information regarding this study and gave their written or oral consent prior to the interview. All participants were assured of the following: (a) their right to withdraw from the study at any time; (b) that participant information would be limited to use within this study.

A total of 31 interviewees participated in the study, comprising 11 administrators (4 females and 7 males) and 20 physicians (8 females and 12 males). The average age of all interviewees was 49.52 years, and all had over 10 years of work experience. 12 individuals had an academic background in Internal Medicine, 6 in Public Health, 6 in Preventive Medicine, 4 in Public Administration, and 3 in Nursing (shown in Table 2).

A total of 32 original concepts related to the VHEP were extracted from the original statements, which were subsequently consolidated into eight open codes, i.e., limitations in implementer resources, low enthusiasm among residents, inadequate training mechanisms, poor cooperation mechanisms, lagging service content, insufficient effectiveness, information silos, policies to be strengthened. Based on open coding and the connotation mining of original concepts, four axial codes were identified: participants, management mechanisms, capacity building, and development foundation. Through the study and synthesis of the relationships between open codes and axial codes, three selective coding were established: cognition, input, and guarantee. The specific coding analysis process was illustrated in Table 3.

Cognition: The implementation process faced significant challenges due to gaps in awareness, competency, and commitment across multiple levels. Among healthcare providers, limited authorization, low self-efficacy, and role ambiguity contributed to diminished engagement. For the public, vaccine hesitancy was exacerbated by concerns regarding cost, misinformation, and a low perceived necessity for vaccination.

Input: Operational weaknesses were evident in training, collaboration, and resource allocation. Training mechanisms were characterized as brief, infrequent, and overly theoretical, which failed to foster practical confidence. Inter-departmental and cross-sector cooperation was obstructed by administrative silos. Additionally, material and financial resources were inadequate, leading to frequent vaccine shortages and a lack of additional compensation for prescribers, which adversely affected sustainability.

Guarantee: The absence of a robust policy framework, infrastructural support, and evaluative foundations posed a threat to long-term viability. Policy frameworks were perceived as exploratory and lacking essential legal safeguards, clear standards, and performance incentives, which undermined confidence among frontline workers. Information systems operated in silos, hindering integrated data tracking. The effectiveness and promotion of vaccination efforts were limited by short implementation timelines, unfocused government advocacy, and insufficient social marketing support (details as shown in Supplementary material).

Through a three-level coding process, this study identified that the implementation of the VHEP policy was contingent upon four foundational elements: participant state, management mechanism, capacity building, development foundation. The core factors that ensured the effectiveness of the VHEP policy include cognition, input, and guarantee. Given constraints such as limitations in implementer resources, low enthusiasm among residents, inadequate training mechanisms, it was essential to enhance individual awareness, increase investment, and improve safeguards to effectively address these challenges. Through the analysis and comparison of the relationships among various codes, this study constructed a model of influencing factors for the VHEP, as shown in Figure 2.

This study identified that community physicians’ awareness and attitudes toward the VHEP policy shaped its implementation outcomes. A notable barrier frequently reported by frontline physicians was their reluctance toward the newly mandated task of “authorized prescription-writing.” This reluctance was attributed to existing workforce shortages, high routine workloads, and the perceived additional burden—concerns that were particularly acute in rural settings, where human resources were described as especially strained (26). Administrators, while acknowledging workload issues, more often emphasized the necessity for a change in attitude and professional commitment. Physicians’ engagement was further influenced by self-reported limitations in knowledge and confidence regarding vaccine indications, a theme that resonated with both urban and rural participants, but was often linked by rural physicians to fewer prior training opportunities. On the demand side, participants acknowledged that residents’ willingness to get vaccinated remains low, with practical considerations being that people perceive themselves as having low health literacy and tend to adopt a passive attitude toward acceptance (27). Urban physicians more frequently cited residents’ concerns about cost and vaccine safety, whereas rural providers highlighted deeper accessibility barriers and stronger influences of local community beliefs. These reported differences underscore the necessity for tailored strategies to enhance “cognition”: empowering physicians may require differentiated support for rural versus urban practitioners, while public engagement strategies need to address locally salient concerns (28).

This study revealed that resource investment—particularly through the two dimensions of management mechanisms and capacity building—significantly shaped the quality and effectiveness of prescription policy implementation. Regarding management mechanisms, VHEP training was widely described by participants as suffering from uniform formats, ambiguous content, a lack of continuity, and insufficient frequency. These identified shortcomings collectively pointed to the need for establishing a sustainable training system with clear objectives, specific content, and a blended online-offline model to support ongoing professional development (29). Concurrently, the absence of a robust evaluation mechanism was notable: because VHEP was not included in the performance standards of primary health institutions, assessment indicators remained vague, and effective incentives were lacking. This not only hindered physicians’ ability to reasonably gauge their workload but also dampened their motivation for clinical promotion. Therefore, it was imperative to develop a standardized and transparent evaluation framework that linked assessment outcomes with appropriate incentives, thereby enhancing engagement at the grassroots level (30). Furthermore, cross-regional collaboration was hampered by inefficient information-exchange channels, leading to unclear responsibilities and implementation conflicts. Establishing a unified project-management team was identified as necessary to clarify roles and improve coordination among stakeholders (31). At the level of capacity building, the program was found to be overly focused on prescription issuance, while extended services such as vaccine science communication and health management remained underdeveloped. Coupled with an unstable supply of non-program vaccines, these limitations constrained service accessibility and the program’s ability to comprehensively address residents’ health needs (32). Program outreach relied predominantly on traditional offline methods, which proved insufficient to effectively cover rural areas. Accordingly, integrating VHEP into long-term health benefit policies and actively utilizing diversified channels—including social media—for science communication were recommended to extend the program’s reach and sustainability (33).

This study found that a favorable social and cultural environment, along with policy support, served as the foundational basis for the effectiveness of the VHEP, which aligned with previous research (34). All participants reported that the VHEP enhanced residents’ awareness of disease prevention and increased their motivation to receive vaccinations. However, individual vaccination failures might lead individuals to forgo subsequent vaccinations (35). In recent years, concerns regarding vaccine safety, anti-vaccination sentiments, and the proliferation of pseudoscientific information about vaccines had exacerbated public anxiety and skepticism, resulting in polarized perceptions and judgments regarding vaccine risks, ranging from complete trust to total denial (36, 37). To address this issue, the government must adopt proactive measures to disseminate scientific information and counter misinformation, thereby restoring public confidence in preventive immunization (38). A critical finding was the perceived lack of legal and policy safeguards for prescribers. Physicians across all sites expressed concerns about potential liability, which made them cautious in promoting vaccines. Administrators acknowledged this as a significant policy gap that requires higher-level resolution. This shared concern among various groups underscores a non-negotiable prerequisite for scale-up: clear legal frameworks and liability protections are essential to secure buy-in from frontline providers. Finally, in terms of future scalability, the research findings indicate that integrating the program into the routine public health system and ensuring stable financial support are critical steps for transforming the VHEP from a project-based initiative into a sustained service (39).