Determinants of Herpes Zoster Vaccine Hesitancy: An Updated Systematic Review Based on the 5C Model

Background/Objectives: Herpes zoster (HZ) represents a substantial public health burden, particularly among older adults and individuals at increased risk of severe disease. Despite effective vaccines, uptake remains suboptimal. This systematic review aimed to update evidence on HZ vaccination willingness, acceptance, and hesitancy, and to classify determinants according to the 5C model: Confidence, Complacency, Constraints, Calculation, and Collective Responsibility. Methods: A systematic literature search was conducted in PubMed, Web of Science, and Scopus from the date of the most recent relevant review (2022) to 15 June 2026. Eligible studies were observational studies assessing HZ vaccine hesitancy, willingness, acceptance, and related determinants among adults. Studies included in the previous systematic review were also reassessed. Study selection and data extraction were independently performed, and methodological quality was assessed using a modified Newcastle-Ottawa Scale. Due to substantial heterogeneity, findings were synthesized qualitatively. Results: Thirty-seven studies were included. Actual HZ vaccine uptake was generally low, despite moderate-to-high willingness in several populations. Healthcare professional (HCP) recommendation was the most consistent facilitator of vaccination. Within the 5C framework, low perceived susceptibility and severity of HZ, particularly its complications, were frequently associated with hesitancy, while vaccine cost, out-of-pocket payment, and limited access represented major constraints. Greater knowledge and awareness of HZ and HZ vaccination were generally associated with greater willingness, although knowledge alone did not consistently overcome hesitancy. Collective Responsibility was the least investigated domain. Conclusions: HZ vaccination uptake remains suboptimal despite favorable vaccination intentions. Strengthening HCP recommendations, reducing financial and structural barriers, and improving risk communication may enhance uptake. The 5C model provides a useful framework for understanding HZ vaccine hesitancy and informing targeted adult immunization strategies.