Healthcare organizations today operate across a complex web of systems, electronic health records, payer platforms, lab networks, pharmacy systems, patient-facing applications, and population health tools. Each of these systems generates and consumes clinical and administrative data. The challenge has never been the absence of data but in the difficulty of moving it reliably between systems when and where it is needed.

HL7 and FHIR are the dominant standards governing how that movement happens. Understanding them through the lens of the business problems they address, rather than their technical specifications, provides a more useful foundation for product and organizational decision-making.

A summary of care provided to a patient during a hospital stay should be provided to the patient’s primary care physician at the time of the patient’s discharge from the hospital. Unfortunately, this information is often late, in the wrong format, or never received by the primary care physician. Clinic staff often do not have access to lab results from outside health systems that the patient may have visited in the past month. In addition, the care manager trying to identify high risk patients in a population of patients may be working based on information that is weeks old and incomplete.

These loopholes in the clinical workflows today result in significant costs and poor quality of care due to duplicate tests and treatments, medication errors, inefficient and fragmented care processes, preventable re-admissions.

The underlying problem here is that there are systems that hold the data and there are systems that need that data. That data needs to move between these systems. HL7 and FHIR define a common language that can be used to move the data between systems.

Areas of Operation of HL7 v2 in Clinical Data

HL7 Version 2 is a 30-year-old standard that has managed most of the structured clinical data exchange within hospitals. Today it is so ubiquitous that most health care organizations interact with it daily, without knowing that they are using the standard.

Admissions, Discharges, and Services/Transport Information: This message type is sent when a patient is admitted to a hospital. It advises other systems (e.g., EHRs, billing, care management tools) that the person is now a patient at that hospital.

Information contained in the message can also be sent to external care coordinators. This real-time information is used as the basis of many care transitions. Organizations building alerting or care coordination products that need to know when a patient enters or leaves a facility are certainly working with the ADT feeds.

Laboratory Results: Lab systems communicate results back to ordering providers and EHRs through HL7 v2 ORU (observation result) messages. Any product that surfaces lab data, clinical decision support tools, chronic disease management platforms, patient-facing health records, will encounter this message type in integrations with health system lab infrastructure.

Orders and Referrals: HL7 v2 ORM and OMG message types manage the transmission of orders between systems. Radiology orders, referrals to specialists, and medication orders within care settings frequently move through v2 interfaces.

The practical implication for product and integration strategy is straightforward: v2 is not a legacy concern that can be set aside. Any product that requires real-time clinical event data from hospital environments will need to manage v2 message formats, either directly or through an integration layer.

Where Fast Healthcare Interoperability Resources (FHIR) Change the Equation

FHIR, on the other hand, addresses a different and especially important use case: on-demand access to structured patient data, whereas HL7 focuses on established clinical workflows in the ehr system through event-driven line messaging and remains one of the existing interfaces used for health information exchange.

Patient Data Portability: There is now a regulatory requirement in the United States for certified EHRs, as well as Medicare and medicaid services payers, to expose patient access through the fhir api. This helps organizations provide access to records in ways that support patient access requirements, patient portals, and mobile apps. It gives patients the ability to retrieve their own health records and share them with healthcare applications of their choosing, which strengthens patient engagement and the overall patient experience. Products in the consumer health space, personal health record apps, chronic condition management tools, fitness and wellness platforms seeking clinical context, and other healthcare providers access this medical data through FHIR. It is easier to get started now than it was five years ago. This is because there are now rules that require health systems to make their data available, rather than each system deciding on its own. As a result, the barriers that used to make it hard for people to exchange data and use this health information are lower, while patient consent and data privacy still need to be handled carefully.

EHR-Embedded Applications: Major EHR platforms have built app ecosystems around FHIR and the SMART on FHIR authorization framework. Clinical decision support tools, documentation aids, coding assistance applications, and care gap identification products can launch within the EHR workflow and read or write patient data through FHIR APIs. For organizations developing products intended for use by clinicians at the point of care, this is the primary integration pathway into Epic, Oracle Health, and other major platforms. A typical implementation guide defines the specific framework, core specification, data model, and patient resource details these integrations rely on, helping improve healthcare interoperability and broader data interoperability.

Payer-Provider Data Exchange: FHIR is the mechanism through which payers and providers are increasingly exchanging clinical data for care management, prior authorization, and quality reporting purposes. A payer building a care management program needs the clinical context, diagnoses, medications, recent encounters, and information that typically lives in provider EHRs. FHIR APIs offer a method for data sharing that supports real time access to clear and organized information, which is a big improvement over old methods like fax machines, manual record requests, or custom-made connections. This also supports medication management and quality metrics across care settings.

Population health and analytics are crucial for healthcare systems. A special tool called Bulk FHIR was created to make this work. It is an extension of the standard FHIR, which is used for large-scale data extraction. This means health systems and analytics platforms can easily pull big groups of patient data. They use this data for things like population health analysis, quality measurement, and reporting. Many organizations are now building analytics products that need to bridge legacy HL7-based integrations with newer FHIR-based integrations, including electronic health records and related administrative workflows.

Evaluating Vendors and Partners Through the Lens of Healthcare Interoperability

As a decision-maker evaluating potential EHR vendors, integration partners, or technology platforms, it is best to ask the following questions regarding HL7 and FHIR.

• What version of FHIR does the vendor support?
• What specific FHIR resources and operations does the vendor support?

The FHIR standard is very comprehensive. In practice, most vendors do not implement the entire standard but instead support a subset that is most relevant and useful to support your use cases.

Understanding the scope of a vendor’s implementation of the standard for a particular use case is more important than their compliance with FHIR in general.

• How does the vendor support HL7 v2 interface for real-time clinical events? For instance, ADT events, lab results, etc. will typically not be transported using FHIR alone and will require v2 interface.
• How does the vendor manage HL7 v2 integration for real-time clinical event data? For use cases that depend on ADT notifications or lab result delivery, FHIR alone is typically insufficient

A clear answer about v2 support and how the two standards are bridged is a reasonable expectation.

• What implementation guides or profiles does the vendor follow? FHIR allows for significant customization through profiles, extensions and constraints applied to base resources for specific use cases or regulatory contexts.

US Core, Da Vinci, and USCDI are examples of profiles relevant to common use cases in the US market. Alignment between a vendor’s implementation and the profiles one’s product or integration requires is a practical interoperability consideration.

Conclusion

At their core, HL7 v2 and FHIR are two different methods for achieving healthcare data exchange. That they are alike is readily apparent; each is a standard for the exchange of healthcare information. Yet one is a message standard utilized for real-time clinical event messaging within a hospital and is not likely to disappear for many years. The other, a more recent development, underpins healthcare interoperability through a FHIR API for on-demand application access, shaped at the national level by the National Coordinator to support modern interoperability standards. It is the standard for meeting regulatory requirements; the basis of a connected healthcare ecosystem of apps that run on top of EHRs; and a foundation for data sharing between payers and providers that also improves patient access. While the two standards exist to facilitate healthcare data exchange, they also support health information exchange in a meaningful manner, each bringing its own value to the equation.

This understanding of the two standards is particularly important for product managers and decision-makers. Instead of wanting to know the technical details of both standards, they should realize that this understanding of both gives them an idea of where data comes from, how data can be accessed, what integration complexity they have to expect and how they can check the capabilities of systems and partners. Healthcare data exchange is no longer primarily a technical constraint, but increasingly a strategic and operational constraint and the standards that govern the exchange of clinical and non-clinical data are key in this process.

Frequently Asked Question- HL7 and FHIR

1. What is the difference between HL7 and FHIR in healthcare interoperability?

HL7 v2 and FHIR both enable healthcare data exchange, but they serve different purposes. HL7 v2 is primarily used for real-time clinical event messaging, such as patient admissions, discharges, lab results, and orders within hospital environments. FHIR, on the other hand, uses modern web APIs to provide on-demand access to patient data. While HL7 v2 supports operational workflows, FHIR enables mobile apps, patient portals, payer-provider data exchange, and EHR-integrated applications. Most healthcare organizations use both standards together rather than choosing one over the other.

2. Can FHIR replace HL7 v2 completely?

In most healthcare environments, FHIR is not replacing HL7 v2 entirely. Many hospitals and health systems still rely on HL7 v2 interfaces for mission-critical workflows such as ADT notifications, laboratory reporting, and order management. FHIR complements these capabilities by enabling secure API-based access to patient data and supporting modern interoperability requirements. As healthcare ecosystems evolve, organizations often implement integration strategies that bridge HL7 v2 and FHIR to support both real-time events and on-demand data access.

3. Why is FHIR important for healthcare organizations today?

FHIR has become increasingly important because it supports regulatory requirements, patient access initiatives, and digital health innovation. Healthcare providers, payers, and application developers use FHIR APIs to exchange structured clinical information more efficiently than traditional methods. It enables patient portals, care management applications, clinical decision support tools, and population health solutions to access healthcare data securely and consistently. FHIR also helps organizations improve interoperability while reducing the complexity of custom integrations.

4. What should healthcare organizations look for when evaluating a vendor’s interoperability capabilities?

Organizations should look beyond a vendor’s claim of being “FHIR compliant” and assess the specific interoperability capabilities they support. Key considerations include the FHIR version implemented, supported resources and APIs, alignment with implementation guides such as US Core or Da Vinci, and the ability to handle HL7 v2 interfaces for real-time clinical events. Understanding how a vendor bridges HL7 v2 and FHIR is critical because many healthcare workflows depend on both standards working together seamlessly.