Vaccination represents one of the most effective public health interventions for preventing infectious diseases and protecting child health (1, 2). Vaccines have contributed significantly to reducing childhood morbidity and mortality worldwide, making immunization programs essential components of comprehensive healthcare systems (3).

China has implemented extensive childhood immunization programs for decades, achieving substantial improvements in child health outcomes (4). Following the promulgation of regulations on vaccine circulation and vaccination administration, various regions have actively developed immunization programs according to local conditions (5). However, vaccination policy implementation varies significantly across different local governments (6). With rapid economic development, Chengdu has experienced dramatic increases in migrant populations, with many migrant children accompanying their working parents to urban areas, creating new challenges for routine immunization management (7).

In China's National Immunization Program, vaccines are classified into two categories: Category I vaccines are mandatory and provided free of charge by the government, while Category II vaccines are optional and require out-of-pocket payment (8). This classification system significantly influences parents' vaccination decisions and knowledge needs, particularly regarding the importance and safety of Category II vaccines (9).

Parents and guardians serve as primary decision-makers for children's vaccination, and their knowledge, attitudes, and practices directly affect vaccination uptake and immunization coverage rates (10, 11). Recent studies have demonstrated positive correlations between guardian vaccination knowledge levels and successful immunization program implementation (12, 13). Furthermore, educated guardians can serve as health educators within migrant communities through “peer education” mechanisms, extending vaccination knowledge to broader populations (14).

Guardian participation in vaccination decisions proves valuable for smooth immunization program implementation and reduction of vaccine-preventable diseases (15, 16). Research from various settings has shown that comprehensive knowledge-attitude-practice (KAP) assessments provide essential insights for developing targeted health education interventions and improving vaccination services (17, 18).

However, limited research has examined vaccination KAP among guardians in major Chinese cities like Chengdu, particularly considering the unique challenges posed by mixed local and migrant populations. This study was conducted to assess vaccination knowledge, attitudes, and practices among guardians of preschool children in Chengdu, providing evidence for developing improved immunization strategies, enhancing vaccination service quality, and better controlling vaccine-preventable diseases.

This cross-sectional study is the first to quantify childhood-vaccination knowledge, attitudes and practices (KAP) among guardians in a rapidly urbanising district of Chengdu that hosts a large migrant population. Three headline findings emerged. First, overall attitudes were strongly positive—more than four in five guardians endorsed the necessity of vaccination—yet substantial knowledge gaps remained, especially for Category II (self-paid) vaccines, with only one third recognising their importance. Second, socioeconomic gradients were pronounced: higher education, income and home ownership independently predicted better knowledge scores. Third, exposure to negative media reports was common and strongly associated with hesitant attitudes. Taken together, these results identify an urgent need for more nuanced, equity-focused communication strategies.

Participants in our study displayed a level of knowledge about Category II vaccines that aligns with results from an earlier investigation conducted in an inland setting, yet still trails behind the knowledge documented in a more economically developed coastal metropolis (24, 25). This gap is probably shaped by a combination of factors, including local economic conditions, the distribution of educational resources, the reach and intensity of public-health messaging, and how readily residents can access trustworthy health information. The regional discrepancy supports the notion that economic development and health-information infrastructure jointly shape vaccine awareness. Outside China, Wilson et al. reported that only 60% of French nurses recommended routine childhood immunisation (26), illustrating that professional endorsement alone does not guarantee universal parental confidence. Conversely, the 85.1% positive-attitude rate in our study exceeds the 71.0% reported in a United States HealthStyles survey during the same period (27), suggesting that guardians in Chengdu remain broadly supportive of the national immunisation programme despite media scandals.

The socioeconomic patterning we observed aligns with health-literacy theory, which posits that people with greater resources have better access to information and a higher capacity to evaluate conflicting claims (28, 29). For migrant families, structural barriers—unstable housing, time-poor employment and weaker social networks—likely limit exposure to reliable sources and magnify the impact of sensational online content. Kata has shown that anti-vaccine messages circulate rapidly on social media platforms by exploiting emotive storytelling and distrust of authorities (30). Our finding that barely a quarter of guardians remain unaffected by negative media underscores the need to inoculate parents against misinformation before crises erupt.

Based on these insights, three tiers of intervention appear feasible. First, strengthen point-of-care education: brief, image-rich modules delivered by vaccination nurses during observation periods can cover Category II indications, safety profiles and adverse-reaction management. Evidence from Hu et al. indicates that such micro-learning sessions significantly improve COVID-19 vaccine intent (31), and the same principle should translate to routine childhood vaccines. Second, leverage digital tools already embedded in daily life. Integrating a “smart reminder” function into existing WeChat health mini-programmes would allow guardians to scan the child's vaccination certificate and receive algorithm-tailored messages at key decision points, an approach supported by the favourable uptake of QR-code health passes during the pandemic. Third, embed vaccination messaging in migrant-friendly community venues—factory dormitories, urban villages and evening clinics—because caretakers in these settings report trusting peer advice over official brochures (32). Materials must be linguistically plain and visually guided to accommodate low functional literacy.

Economic considerations also merit attention. Although willingness to pay for Category II vaccines in our sample was only 41.5%, the figure exceeds the uptake recorded in Shanghai's migrant districts (<30%) (10). Progressive subsidy schemes—partial reimbursement for children from low-income households—could close the affordability gap while preserving consumer choice. Policymakers should pilot such schemes in high-migration wards and evaluate cost-effectiveness alongside educational interventions.

Several limitations warrant caution. The cross-sectional design precludes causal inference, and self-report may inflate desirable practices through social-desirability bias. Although we attained a 90% response rate, the single-centre setting may limit generalisability to rural Sichuan or other megacities. In addition, the KAP instrument, while demonstrating acceptable reliability (α = 0.82), has yet to be validated in non-Mandarin-speaking populations. Future work should (i) employ longitudinal designs to test whether tailored education improves actual Category II vaccination uptake over time, (ii) replicate our survey in multiple provinces to examine regional heterogeneity, and (iii) apply item-response theory to refine the questionnaire and establish normative cut-offs for “adequate” knowledge.

Guardians in Chengdu demonstrate positive attitudes toward childhood vaccination but require enhanced knowledge, particularly regarding vaccine categories, safety profiles, and adverse reaction management. Socioeconomic factors significantly influence vaccination knowledge levels, suggesting need for targeted educational interventions among vulnerable populations. Strengthening healthcare provider communication skills and developing comprehensive, culturally appropriate educational materials could substantially improve vaccination coverage and child health outcomes in this rapidly urbanizing population.