Frequently Asked Questions — HL7, FHIR, VN Core IG

HL7 basics (Q1–Q10)

Q1. What is HL7?

HL7 (Health Level Seven International) is a non-profit health data standards organization founded in 1987 in the United States. The name "Level 7" refers to the Application layer of the OSI model. HL7 develops four main standard families: v2, v3, CDA, and FHIR. Read the full article: "What is HL7".

Q2. Are HL7 and FHIR the same thing?

No. FHIR is one of HL7's four standard families, alongside HL7 v2, HL7 v3, and CDA. FHIR arrived last and combines the message-based strengths of v2 with a modern RESTful design. When people say "HL7" in technical contexts, they often mean HL7 v2 specifically.

Q3. Does Vietnam have an HL7 Affiliate yet?

As of April 2026, Vietnam does not yet have an official HL7 Affiliate. The community initiative hl7.org.vn, launched by Omi HealthTech (part of OmiGroup), is working toward establishing an HL7 Vietnam Affiliate. Doing so requires alignment with the Ministry of Health, professional associations, and HL7 International.

Q4. Is HL7 free?

HL7 standards have been published free of charge since 2013 under the "Free IP" program. Organizational membership is paid and scaled to national GDP. FHIR is uniquely free to use and redistribute under the CC0 (public domain) license.

Q5. Is HL7 v2 obsolete?

Not yet. About 95% of hospitals worldwide still rely on HL7 v2 for ADT (Admit/Discharge/Transfer), lab, pharmacy, and radiology traffic. HL7 v2 is expected to coexist with FHIR for the next 10 to 15 years. Most legacy HIS, LIS, and RIS systems in Vietnam still use v2 internally.

Q6. Is HL7 v3 still in use?

Sparingly. HL7 v3 is mostly seen at the UK NHS, in some German states, and in Korea. Greenfield projects starting from 2024 onward should not pick v3 — FHIR is a better choice on every axis. Vietnam has virtually no significant v3 deployments.

Q7. What is CDA?

CDA (Clinical Document Architecture) is a document standard built on HL7 v3, used for discharge summaries, referral letters, and clinical summaries. FHIR Composition and Bundle are gradually replacing CDA for new use cases thanks to a simpler grammar.

Q8. Who uses HL7 in Vietnam?

Private hospitals (Vinmec, FV, Hoan My), some central hospitals (Bach Mai pilots), and international PACS/LIS vendors. There is no Vietnamese legal mandate for HL7 yet, but Circular 13/2025/TT-BYT on electronic medical records opens the door for FHIR adoption.

Q9. Where can I learn HL7?

The official spec lives at hl7.org. Hands-on training is widely available through vendors such as Mirth Connect and HAPI FHIR. HL7 International also runs accredited online courses. A Vietnamese-language community is taking shape at hl7.org.vn.

Q10. How do HL7 and DICOM differ?

HL7 carries text-based data: ADT, lab, prescriptions, and clinical records. DICOM carries medical imaging: X-ray, CT, MRI, and ultrasound. The two standards complement each other rather than competing. FHIR's ImagingStudy resource links to a DICOM Study UID.

FHIR basics (Q11–Q20)

Q11. What is FHIR?

FHIR (Fast Healthcare Interoperability Resources) is HL7's healthcare API standard built on RESTful HTTP plus JSON or XML. DSTU1 launched on 30/09/2014. FHIR follows an "80/20" design principle: cover the 80% of common use cases, and let the remaining 20% extend via Extensions. Read the full article: "What is FHIR".

Q12. How is FHIR pronounced?

Pronounced "fire" /faɪər/ — the same as the English word for flames. Avoid spelling out the letters as "F-H-I-R".

Q13. How many Resources are in FHIR?

FHIR R4 (4.0.1) defines 146 Resources mixing Normative and STU (Standard for Trial Use) levels. A subset has reached stable Normative status (Patient, Observation), while others remain Trial Use and may receive minor adjustments in future versions.

Q14. Which FHIR version should I use?

R4 (4.0.1) is the default for every National IG: US Core, JP Core, KR Core, CH Core, and VN Core. R5 shipped in 2023 but is not yet universal — most of the ecosystem (HAPI, vendors, payers) still prioritizes R4. See the FHIR version comparison.

Q15. Does FHIR use JSON or XML?

Both are officially supported. JSON is more popular in practice. A FHIR server must support at least one. HAPI FHIR, Microsoft FHIR Server, and Firely Server all support JSON, XML, and Turtle (RDF).

Q16. Will FHIR replace HL7 v2?

It will gradually over the next 10 to 15 years, but for now both standards coexist. The common pattern is HL7 v2 for internal HIS/LIS/RIS legacy integration and FHIR for public APIs and cross-organization exchange.

Q17. Is FHIR free?

Yes. The spec is free under CC0. Open-source FHIR servers are abundant: HAPI (Java), Microsoft FHIR Server (.NET), and Google Cloud Healthcare API includes a free tier. Commercial vendors offer managed FHIR services with SLAs and support.

Q18. Where can I find a public FHIR sandbox?

HAPI FHIR public test server: http://hapi.fhir.org/baseR4. Firely public server: https://server.fire.ly. Both servers are good for trying out the REST API without standing up your own.

Q19. What is SMART on FHIR?

SMART on FHIR is the OAuth 2.0 plus OpenID Connect spec for FHIR app launch context. Apple Health, Epic MyChart, and Cerner all use SMART so third-party apps can access patient data with explicit consent. It is the foundation for the patient-facing app ecosystem.

Q20. How do FHIR and openEHR differ?

They follow different paradigms. FHIR is an exchange API — focused on moving data between systems. openEHR is an EHR storage architecture with archetypes and templates — focused on long-term persistence. You can combine them: openEHR backend with a FHIR API at the edge. Read the full comparison.

VN Core IG (Q21–Q30)

Q21. What is VN Core IG?

VN Core IG is an Implementation Guide that constrains FHIR R4 for the Vietnamese healthcare context. It contains Profiles (Patient, Encounter, Coverage, Claim, etc.), Extensions (ethnicity, BHYT, level of care), and Terminology (ICD-10 VN, the 34 provinces, the 54 ethnic groups, and more). See the about page.

Q22. What is the current VN Core IG version?

Version 0.5.0 (community draft, as of April 2026). It is the milestone preceding the release candidate. The official 1.0.0 release is planned for Q3 2027 once pilots at three to five hospitals wrap up and the community has had time to weigh in.

Q23. Where is the VN Core IG repository?

There are two main sources: the Ministry of Health IT Department repo at github.com/hl7vn/vn-core-ig (a 2024 draft, infrequently updated), and the Omi HealthTech community initiative at github.com/HL7-org-vn (under active development). The long-term goal is to merge both branches.

Q24. What is the canonical URL for VN Core?

Community canonical URL: http://fhir.hl7.org.vn/core/. The previous Ministry of Health build used http://fhir.ehealth.gov.vn/core/. Once formal collaboration begins, the canonicals can be merged or redirected.

Q25. Which Profiles are in VN Core IG?

VN Core v0.5.0 ships 52 Profiles: VNCorePatient, VNCorePractitioner, VNCoreOrganization, VNCoreEncounter, VNCoreCondition, VNCoreObservation, VNCoreCoverage, VNCoreClaim, VNCoreExplanationOfBenefit, VNCoreMedicationRequest, and many more. All of them follow the naming convention VNCore{Resource}.

Q26. Which Extensions does VN Core IG provide?

VN Core v0.5.0 includes 47 Extensions: ethnicity (54 groups), commune/ward (3,321 units after Resolution 202/2025/QH15), BHYT card details (beneficiary class, registration site, validity), level of care, hospital rank, practitioner license number, academic title, and legacy administrative codes.

Q27. Which CodeSystems does VN Core IG cover?

VN Core v0.5.0 contains 70 CodeSystems and 75 ValueSets: ICD-10 VN (Decision 4469/QĐ-BYT), ICD-9-CM 2026 (Decision 387/QĐ-BYT), the 54 ethnic groups, the 34 provinces (Resolution 202/2025/QH15), BHYT beneficiary classes (Decision 3276/QĐ-BYT), levels of care, hospital ranks, partial LOINC, SNOMED CT VN (three releases), traditional Vietnamese medicine (Decisions 2552/QĐ-BYT and 3080/QĐ-BYT), and many other domain-specific code sets.

Q28. Can I contribute to VN Core IG?

Yes. The project is published under CC-BY-4.0 and welcomes pull requests from the community. Welcome contributions include new profiles, real-world business extensions, test data, documentation translations, and bug reports. See the governance model.

Q29. Does VN Core conflict with the Ministry of Health IG?

No. The goal is collaboration and a future merge once the Ministry of Health is ready. The two canonical URLs can redirect to each other during the transition. The Omi HealthTech team has already opened conversations with the developers behind the Ministry's build.

Q30. When will VN Core 1.0 ship?

Planned roadmap: a Q4 2026 release candidate (RC1) once pilots wrap up, followed by the official 1.0.0 in Q3 2027. Every milestone may shift based on pilot outcomes and feedback from HL7 International.

BHYT & XML 4210 (Q31–Q35)

Q31. Is XML 4210 still in use?

Yes (as of April 2026). Note, however, that "XML 4210" is a legacy shorthand based on the older Decision 4210/QĐ-BYT. The current legal basis for the data standard submitted to Vietnam Social Security (BHXH) is Decision 130/QĐ-BYT, amended by Decision 4750/QĐ-BYT, and most recently Decision 3176/QĐ-BYT (29/10/2024). Formal technical documents should refer to it as Decision 3176.

Q32. Will FHIR replace XML 4210?

There is no formal regulation mandating a replacement yet. However, Decree 164/2025/NĐ-CP on electronic transactions in social insurance (effective 29/06/2025) opens the door for two-way digital APIs with Vietnam Social Security (BHXH), and FHIR is the leading candidate as the exchange format.

Q33. How do I map XML 4210 to FHIR?

The core mapping: Coverage corresponds to the BHYT card, Claim to the payment request, and ExplanationOfBenefit to the settlement response. VN Core IG ships ConceptMaps for every XML 3176/4210 field. Read the article: "FHIR and BHYT".

Q34. What is new in Decision 697/QĐ-BYT?

Decision 697/QĐ-BYT, issued 19/03/2026, defines the new BHYT cost itemization template with 12 categories, 13 columns, and multi-BHYT support (multiple cards on a single encounter). It takes effect on 19/03/2026; transition and software upgrades must complete by 01/07/2026. It supersedes Decision 6556/QĐ-BYT (2018) during the transition.

Q35. Does Decree 188/2025 set a universal payment cap?

No. Decree 188/2025/NĐ-CP (effective 01/07/2025) sets caps and benefit levels per cost category (medications, medical supplies, technical procedures, hospital beds), not a single universal number for Claim.total. VN Core uses the cumulativeCopay extension to model running co-payment totals; detailed caps and benefit levels live in the rules engine or the BHXH integration gateway, not in base profile invariants.

Legal framework (Q36–Q42)

Q36. What does Circular 13/2025/TT-BYT require?

Circular 13/2025/TT-BYT (effective 21/07/2025) requires electronic medical records to link to the personal identification number or a VNeID account, carry a digital signature per Decree 137/2024/NĐ-CP, and comply with the Medical Examination and Treatment Law 2023. Timelines: hospitals by 30/09/2025; other healthcare facilities by 31/12/2026.

Q37. What does Decree 278/2025/NĐ-CP require?

Decree 278/2025/NĐ-CP mandates data connection and sharing between government agencies and information systems. It took effect on 22/10/2025 (the date of issue). Standardization and unified connections must be in place by 31/12/2026. The decree directly affects every health system that needs to interoperate with national databases.

Q38. What does Personal Data Protection Law 91/2025 cover?

The Personal Data Protection Law (Law 91/2025/QH15, effective 01/01/2026) classifies health data in the highest sensitivity tier. It requires explicit consent, audit trails, a Data Protection Officer (DPO), a Data Protection Impact Assessment (DPIA), and breach notification within 72 hours. Penalties reach 5% of prior-year revenue. Read the article: "FHIR and the Personal Data Protection Law".

Q39. Does Decree 356/2025 replace Decree 13/2023?

Yes. Decree 356/2025/NĐ-CP (effective 01/01/2026) fully supersedes Decree 13/2023/NĐ-CP. Every new technical and legal document must reference Decree 356/2025; do not cite the now-defunct Decree 13/2023. Decree 356/2025 provides the detailed implementation rules for Law 91/2025.

Q40. Does AI Law 134/2025 apply to healthcare AI?

Yes. The AI Law (Law 134/2025/QH15, effective 01/03/2026) classifies AI systems into three risk tiers. Healthcare AI typically falls in the high-risk tier and must register, undergo periodic audits, and keep a human in the loop for clinical decisions. Read the article: "FHIR and the AI Law".

Q41. What does Decree 90/2026 penalize?

Decree 90/2026/NĐ-CP covers administrative penalties in the health sector (effective 15/05/2026). Specific penalty amounts for EMR compliance and data interoperability should be checked directly against the decree text for each concrete case; do not extrapolate beyond the issued provisions.

Q42. Can personal data be stored outside Vietnam?

A cross-border data transfer impact assessment is required, using Form 09 of Decree 356/2025/NĐ-CP. Practical recommendation: host the FHIR server inside Vietnam to lower compliance risk and meet the data residency expectations of the 2018 Cybersecurity Law (Law 24/2018/QH14).

Hospital implementation (Q43–Q50)

Q43. Do small hospitals need FHIR?

Yes if the hospital needs to interoperate with Vietnam Social Security (BHXH), VNeID, the personal health record, or to exchange data with upper-tier hospitals as required by Decree 278/2025/NĐ-CP. A purely internal operation can stay on HL7 v2 — but should set a FHIR roadmap for the next 2 to 3 years.

Q44. What is the cost estimate for a Class II hospital?

Roughly VND 1 to 3 billion over 12 to 18 months for the "FHIR layer over a legacy EMR" pattern. That covers HL7 v2 to FHIR integration, profiling against VN Core, terminology mapping, and engineering training. See the article: "For hospital CIOs".

Q45. Can I self-host a FHIR server?

Yes. Open-source HAPI FHIR runs on a VPS for VND 5 to 20 million per month depending on scale. You keep data sovereignty and meet data residency requirements. You will need a DevOps team comfortable with Java and PostgreSQL. No separate license fee is required.

Q46. Which FHIR vendors operate in Vietnam?

Major international vendors (Carestream, Siemens Healthineers, Fujifilm, Epic) already ship FHIR modules. Domestic vendors are catching up: Omi HealthTech and several large HIS vendors have piloted FHIR APIs. Reach out via the hl7.org.vn community page to keep up with the latest list.

Q47. How long does HL7 v2 to FHIR migration take?

Roughly 3 to 5 years for large hospitals with several legacy systems. Greenfield hospitals or those replacing the HIS wholesale can go FHIR-first in 6 to 12 months. The realistic pattern is to run v2 internally and FHIR for public APIs in parallel, then phase v2 out gradually.

Q48. Do I have to replace my current EMR?

Not necessarily. The most realistic pattern is to add a FHIR Façade (an adapter layer) on top of the legacy EMR or HIS, exposing a REST API outward without touching the backend. This is the approach Epic, Cerner, and many enterprise systems take. Full EMR replacement only makes sense when the legacy system has reached end-of-life.

Q49. How long does FHIR EMR training take for clinicians?

Clinicians do not need to learn FHIR — they use the new EMR UI. Training averages 1 to 2 weeks to get comfortable with the UI, workflows, and shortcuts. FHIR is a technical standard underneath, fully invisible to end users.

Q50. How do I join the VN Core IG community?

GitHub: github.com/HL7-org-vn. Website: hl7.org.vn. Email: [email protected]. Visit the community page for additional discussion channels and events.

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