VCAC: A Blockchain-Based Virtual Care Access Control Model for Transforming Legacy Healthcare Information Systems and EMRs into Secure, Interoperable Patient-Centered Virtual Hospital Systems

The rapid rise of virtual hospitals has created an urgent need for secure, interoperable, and patient-centered (PC) access to medical data across distributed healthcare environments. However, most existing hospital information systems and electronic medical records (EMRs) were not designed to support decentralized service delivery or cross-institutional collaboration. While many prior solutions advocate replacing legacy systems with new architectures, such approaches often face significant cost, integration, and adoption challenges. This paper introduces a novel blockchain-based Virtual Care Access Control (VCAC) model that extends—rather than replaces—legacy systems and EMRs to support secure data sharing across virtual hospital ecosystems. Leveraging the core features of distributed ledger technology (DLT)—including immutability, decentralized auditability, and consensus-driven access—the VCAC framework embeds a six-tier PC information classification scheme into a blockchain-based layer. This model enables fine-grained, role-based access to clinical data, supporting PC treatment in comorbidity-aware contexts, emergency access, and policy-driven governance while maintaining institutional autonomy. We demonstrate how VCAC mitigates key confidentiality, integrity, and availability risks common to legacy systems. The model is evaluated through a breast cancer outpatient use case, illustrating its practical potential to transform fragmented infrastructures into secure, interoperable, and PC virtual care platforms—without disrupting existing healthcare operations.