Factors Associated with Prescription-to-Vaccination Conversion and Timeliness: A Real-World Analysis

Background: This study evaluated vaccine prescription conversion and identified associated factors in Henan Province, China, during 2025. Methods: The study was conducted in Lingbao City, Henan Province. All vaccine prescriptions issued in 2025 were collected, and vaccination status was linked through the Henan Provincial Immunization Information Management System. Subgroup analyses were stratified by vaccine type (NIP vs. non-NIP). Univariate analyses used χ2, Mann–Whitney U, and Kruskal–Wallis H tests. Multivariable analyses employed Firth-corrected logistic regression for conversion behavior, and mixed-effects models with random intercepts for patient ID for conversion timeliness, analyzed using a two-part model. All analyses were performed using R software (version 4.5.3). Results: Among 50,887 prescriptions, the overall conversion rate was 13.8%. NIP vaccines had a higher conversion rate than non-NIP vaccines (76.8% vs. 12.5%, p < 0.001) and a higher same-day conversion rate (13.9% vs. 7.4%; χ2 = 59.585, p < 0.001), but longer delays among non-same-day conversions (23 vs. 4 days). Manual prescriptions were associated with significantly higher conversion in both NIP (OR = 3.913) and non-NIP (OR = 37.720) subgroups. Vaccination clinics were associated with a nearly 20-fold higher odds (OR = 19.386). Interaction analyses showed manual prescriptions were more strongly associated with conversion and shorter delays in older adults, and had stronger associations with conversion for non-NIP vaccines (χ2 = 22.275, p < 0.001). Vaccination clinics were most strongly associated with conversion in children (ΔP = 0.130); however, the improvement in same-day conversion among older adults was relatively smaller, suggesting additional barriers beyond clinic availability may exist in this population. Conclusions: Manual prescriptions and vaccination clinics were associated with higher vaccine prescription conversion, with particularly pronounced effects on non-NIP vaccines. Older adults exhibited the lowest conversion rates. In parallel with promoting electronic prescriptions, co-issuing paper prescriptions is recommended, particularly for non-NIP vaccines and older adults.