Why does health data need its own trust infrastructure layer?
Fragmented medical records are a global problem
According to the World Health Organization, a cancer patient generates medical data across an average of 8–12 different healthcare facilities over a three-year period. In Vietnam, with its multi-tier health system and a population of over 100 million, fragmentation is even more severe data is split across tiers and facilities.
The result: when a patient transfers hospitals, doctors must start from scratch, repeat duplicate tests, and sometimes miss critical information about drug allergies or medical history. The Ministry of Health estimates that 15–20% of healthcare costs in Vietnam stem from duplicate testing caused by a lack of data interoperability.
Data ownership - a legal question without a clear answer
One fundamental question remains unresolved globally: who owns medical records? Hospitals that generate the data want to retain control; patients, as the subjects, want ownership; while insurers and other stakeholders need access to operate the system.
In Vietnam, the Personal Data Protection Law 2025 and the amended Law on Medical Examination and Treatment have established a clearer foundation: patients are the data subjects, and other parties may only access data within the scope of granted and verifiable permissions. However, this legal principle only has real value when backed by appropriate technical infrastructure, where access is controlled, recorded, and cannot be abused. This is precisely the gap that the national blockchain is designed to fill.
Special technical requirements of health data
Health data has three characteristics that place stringent demands on storage and sharing infrastructure:
Immutability and auditability: every change to a medical record must be logged and cannot be deleted or altered without authorisation. This is also a requirement under the Law on Medical Examination and Treatment.
Immediate availability: in emergency situations, doctors need instant access to critical information such as blood type, allergies, and pre-existing conditions, there is no room for verification delays.
Absolute privacy: HIV diagnoses, psychiatric records, and genetic information are among the most sensitive data categories; a breach can have severe consequences for the patient.
A traditional centralised system struggles to balance all three requirements simultaneously. This is why a Layer 1 blockchain is seen as a complementary infrastructure layer, one where data can be verified, audited, and access-controlled without compromising security.
🔑 Read more: Vietnam's National Blockchain and the foundation of trust infrastructure in the data economy era
International models: Estonia, EBSI, and South Korea
Case study: Estonia - Blockchain for national health records
Estonia is a world leader in digital health, with 99% of medical records digitised since 2018. The e-Health Estonia platform integrates with KSI Blockchain, a cryptographic timestamping platform that ensures immutability for every record read or write. Patients can actively share their records with doctors via the eID app, and every access leaves a trail on the blockchain.
The core of the Estonian model is that blockchain does not store health data directly, it only stores cryptographic proofs confirming that the data has not been altered. The original data remains at the hospital, ensuring both GDPR compliance and data integrity with full verifiability.
🔑 Read more: Estonia: A pioneer in applying blockchain to the national healthcare system
Case study: EBSI - Cross-border health records across Europe
The European Blockchain Services Infrastructure (EBSI) is implementing a "Self-Sovereign Identity for Healthcare" use case, allowing citizens to carry their health records when moving across 27 EU countries. Each prescription, test result, or vaccination certificate is issued as a Verifiable Credential, linked to the patient's DID.
When seeking treatment in another country, the patient simply presents a Verifiable Presentation. The doctor can immediately verify the validity of the data through the EBSI network, without needing to access the issuing country's system.
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Case study: South Korea - Healthcare DID on the MyData infrastructure
From 2022, South Korea integrated decentralised identity (DID) into its national MyData platform. Every citizen holds a unified digital identity used to access and manage health records at most public hospitals and the majority of private ones.
Through data standardisation and blockchain-based permission mechanisms, patients can grant doctors access to their records in just seconds. A doctor in Seoul can view MRI results from Busan almost instantly, with no need to synchronise systems between hospitals.
Identity standardisation is a prerequisite for health data interoperability. When each patient has a unique DID and controls their own access permissions, the system can share data quickly and accurately while preserving privacy.
Domain chain architecture for digital healthcare: NDAChain's approach
NDAChain is designed around a layered multi-chain architecture built on a native root chain, where each sector has its own Domain Chain connected to the Rootchain to ensure consistency and interoperability. This approach allows the system to scale by industry while maintaining a shared trust layer at the national level.
Healthcare Domain Chain - A dedicated chain for health
In its deployment roadmap, NDAChain is building a dedicated Domain Chain for healthcare, centred on three core components:
Patient identity: each person holds a unique DID (did:nda), serving as a universal "key" across all healthcare facilities.
Referenced medical records: clinical data remains stored at the hospital; the blockchain only records a hash and metadata to ensure integrity.
Permission mechanism: patients actively grant or revoke access; every action is digitally signed and fully auditable.
This design directly addresses three major challenges in digital healthcare.
First, verification without data exposure - doctors can verify the validity of a record through cryptographic proof without accessing the full content.
Second, protection of sensitive data - medical information does not leave the hospital system without the patient's explicit consent.
Third, preservation of legal evidence - even if a hospital's system experiences an incident, the blockchain retains an authenticated trace of the record's existence and integrity.
This is a balanced approach between data interoperability and privacy protection, the two core pillars of a modern digital health system.
Zero-knowledge proof for health data
A common scenario: an insurance company needs to confirm that a customer does not belong to a high-risk disease group before issuing a policy. The traditional approach requires submitting the full medical record, exposing a great deal of unnecessarily sensitive information.
With Zero-Knowledge Proof (ZKP) technology on blockchain, users only need to provide proof that "I do not belong to a high-risk disease group" without disclosing any details of their medical history. The insurer can still verify the validity of the information through the shared trust infrastructure.
Privacy and verifiability no longer need to be traded off against each other. ZKP allows health data to be protected at the highest level, while relevant parties can still verify information accurately and instantly.
🔑 Read more: Zero-Knowledge Proof on Blockchain Layer 1: Securing data without revealing information
Four practical application scenarios in Vietnam
1. Interoperability across treatment tiers
A cardiovascular patient receiving treatment at a district hospital is referred to a provincial hospital. Instead of printing paper records or waiting for internal system synchronisation, the receiving doctor instantly accesses a medical summary via the patient's DID, including treatment history, prescriptions, and ECG results digitally signed by the district hospital.
The immutability of the national blockchain ensures the receiving doctor has no reason to doubt the reliability of the data, as every change carries an audit trail and cannot be falsified.
2. Anti-counterfeit drugs through pharmaceutical traceability
According to the Drug Administration of Vietnam, hundreds of counterfeit drug cases are detected each year, primarily involving antibiotics, oncology drugs, and premium branded medicines. With a pharmaceutical Domain Chain, patients can scan a QR code to check the entire supply chain from manufacturing to distribution.
Every step is digitally signed by entities with clear identities, eliminating the possibility of falsification or data injection.
3. Vaccination and health certificates with international validity
After the COVID-19 pandemic, the need for an internationally recognised "health passport" has never been more urgent. With DID infrastructure compliant with W3C standards, a vaccination certificate issued by a Vietnamese hospital can be verified by border authorities of any country supporting the standard, without intermediaries, without notarised translations.
This is a concrete application of cross-border digital trust, and a clear illustration of why Vietnam's blockchain must be built to international standards from the outset.
4. Medical research with verified anonymised data
Research institutes need large datasets to develop AI-based diagnostic imaging, epidemiological forecasting, and new drug research. But health data cannot be shared freely.
With blockchain, researchers can request a Verifiable Presentation in aggregated form containing anonymised statistics (for example: number of cases of disease X in age group Y), along with cryptographic proof that the source data is authentic, originates from authorised hospitals, and has been processed through the correct anonymisation procedure. Transparency comes from verifiability, not from exposing raw data.
Challenges that cannot be overlooked
Despite its significant potential, deploying blockchain in Vietnam's healthcare sector still faces three practical challenges.
The first is uneven digital infrastructure. Central-level hospitals already have modern Hospital Information Systems (HIS), but many lower-tier facilities still operate on paper or spreadsheets. This requires a phased deployment roadmap starting with ready institutions, then expanding gradually.
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The second is the data ownership mindset. Many healthcare facilities still view patient data as proprietary assets and are not yet ready to share. Changing this requires a clear and consistent legal framework that makes controlled data sharing the new operational standard.
The third is technological capability. Healthcare staff do not need a deep understanding of blockchain, but they do need simple, easy-to-use tools that integrate seamlessly into their daily clinical workflows.
With NDAChain, these challenges are not barriers but an inevitable part of the transition process. The design principle is to keep the technology in the background, so that doctors and patients only experience a system that is simple, reliable, and seamless.
Digital healthcare as a test for national trust infrastructure
Healthcare is the sector with the most demanding requirements for privacy, immutability, and availability and simultaneously the sector where people most directly experience the value of quality national digital infrastructure. When a mother can share her child's vaccination record with a single tap on her phone, when an emergency doctor can read a patient's drug allergy history in seconds, when a patient receives their original test results and knows with certainty they have not been altered that is when digital trust is no longer a concept, but a lived experience.
NDAChain is positioned as the national blockchain infrastructure layer for that journey: not to replace the existing healthcare system, but to connect and complement it ensuring data is verified, interoperable, and returned to the control of patients themselves. When technology stands in the background and trust is placed in the right hands, digital healthcare is not merely a technological transformation, but a transformation of how society operates on data.
👉 Learn more about NDAChain - Vietnam's national blockchain infrastructure - at https://ndachain.vn/en.
