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EHR-IIS Interoperability Expert Panel Project

The EHR-IIS Interoperability Expert Panel Project focuses on three separate and independent technological components: technical interoperability, semantic interoperability, and patient de-duplication.


Technical Interoperability

Technical interoperability concerns the physical transmission and receipt of health data from one system to another through a transport layer technology. This project seeks to provide a recommendation for a standardized transport layer protocol for immunization-related messaging. One of the major components of this project is the formation of a panel of experts to investigate and determine which transport layer technology would most effectively enhance interoperability between IIS and health information systems.

The Transport Layer Expert Panel that formed in January 2011 consisted of 41 industry experts representing the Office of the National Coordinator (ONC), the CDC Public Health Informatics and Technology Program Office (PHITPO), the American Immunization Registry Association (AIRA), the Electronic Health Record Association (EHRA), the Indian Health Service (IHS), IIS vendors, EHR vendors, and IIS programs. The panel conducted a thorough investigation and comparison of four transport protocol options. This involved the evaluation of each protocol against 20 agreed-upon business requirements, as well as the HL7 2.5.1 Use Cases. The panel's intent was to identify and recommend a unified technical interoperability framework for immunization-related transport that would allow for both broad adoption and long-term viability as an industry standard.

Through numerous remote working sessions and a three-day, in-person session in Atlanta in early March 2011, the panelists came to the consensus that SOAP Web Services is the recommended standard. The other evaluated protocols were ebXML, HTTPS, and SMTP + S/MIME. While the panel recommends SOAP, it significantly acknowledges the role and value of the other transport layer options. It is not the expectation of the panel or of the EHR-IIS Interoperability Project that IIS programs discontinue the use of existing transport protocols or those currently under development. The panel's findings do not represent a mandate for IIS programs but rather a recommendation in an effort to move towards standardization across the immunization messaging community.


The panel's findings were formally presented at the National Immunization Conference (NIC) in March 2011. The collaborative work of the panel was documented in a 75-page Recommendations document which details the panel's methodology, justifications for its recommendation, detailed acknowledgement of the other transport protocols, and a summary of the impacts of a SOAP implementation.

  • Transport Layer Protocol Recommendation [75 pages]
    This document details the panel's methodology, justifications for its recommendation, detailed acknowledgement of the other transport protocols, and a summary of the impacts of a SOAP implementation.


To support the SOAP recommendation, the expert panel developed resources to support software interface engineers and technical project managers.

  • SOAP Implementation Resources
    Case studies of SOAP implementation efforts, lessons learned, and documentation of SOAP tools, including coding samples for the WSDL in Java and .Net.
  • Formal Specification (v1.2)[13 pages] (Updated Sep 2015)
    Describes transport, security, and SOAP operations, parameters, and faults for SOAP-based HL7 submissions and queries to an IIS.
  • SOAP Transport Protocol Mini-Guide [4 pages]
    A summary of the recommendation of SOAP and its impacts, supported by IISSB efforts to recommend a standard transport option that grantees and other healthcare systems would support for immunization interoperability.


Panelists and Project team members worked with the AIRA Education Steering Committee to provide two informative educational webinars on the SOAP protocol during October 2011 and March 2012.

  • The IIS Transport Layer 101 webinar provided an entry-level educational and programmatic overview for various non-technical staff of IIS and their IT departments.
  • The IIS Transport Layer 201 webinar expanded on the first webinar by providing technical details for implementers using or Java technologies.

Additional “How To” guides have been made available on the AIRA website.

Source Code Samples

Reference Implementation

The Open Immunization Software project has created a reference implementation which focuses on the core transport operations defined in the WSDL and can serve as a testing service for implementers.

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Semantic Interoperability

Semantic interoperability refers to the ability to automatically interpret the information exchanged meaningfully and accurately in order to produce useful results as defined by the end users of multiples systems. To achieve semantic interoperability, both sides must refer to a common information exchange reference model, which for the IIS community has been defined as Health Level 7 (HL7) messaging. This project focused on developing tools to aid in HL7 immunization-related messaging towards the promotion of health system interoperability. One of the major components of this project was the formation of a panel of experts to address the challenges faced by vendors in interpreting local HL7 2.5.1 Implementation Guides and contracting RFP documentation due to the variance among IIS programs.

The HL7 Messaging Expert Panel that formed in February 2011 was composed of 31 industry experts representing the AIRA, EHRA, IIS vendors, EHR vendors, and IIS programs. The panel supported the development of the following useful tools for IIS programs:

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Patient De-duplication

Patient de-duplication is the process of removing redundant patient records from a database, preventing fragmented and duplicate information from being processed and ensuring that updates and queries apply to the correct record.

Inconsistencies in determining which records represent the same patient, as well as errors in combining patient’s immunization records, negatively affect the overall data quality and usefulness of Immunization Information Systems (IIS).

To address the problem of duplicate patient records, the Centers for Disease Control and Prevention (CDC) established the Patient Data De-duplication Expert Panel. The panel consists of 14 industry experts representing the CDC Public Health Informatics and Technology Program Office (PHITPO), the American Immunization Registry Association (AIRA), the American Academy of Pediatrics (AAP), the Indian Health Service (IHS), IIS vendors, EHR vendors and IIS programs.

The De-Duplication Expert Panel seeks to address the following:

  • Identify data that will enhance the quality of the de-duplication engine
  • Review existing data within the patient de-duplication process (retrospective data cleansing)
  • Address manual review and the merge/unmerge process
  • Create a robust testing methodology/test cases
  • Identify best practices in evaluating a de-duplication engine

Members of the de-duplication panel participated in a very successful in-person session in Atlanta, GA in late February 2012. The facilitated session included a discussion of practice-based solutions for evaluating IIS patient-level de-duplication software approaches and capabilities; practice-based IIS patient-level de-duplication solutions around manual data entry, incoming data and existing patient data; best practice manual review processes and techniques; and specifications for an updated, robust, patient-level, de-duplication test toolkit and test cases including the considerations of sensitivity and specificity.

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Technical Environment Template

A technical environment template has been developed by the IIS interoperability expert panel to be used by an IIS to accurately describe their technical environment. This template may be used in various settings including hardware documentation, future planning, and RFP artifacts.

Technical environment template [2 pages]
NOTE: This same template is available in accessible PDF format [2 pages]

Sections in this template include:

  • Data volume and usage
  • Server definition and usage
  • Server/network diagram
  • Backup/recovery planning
  • Data migration
  • Data exchange documentation


For information on the CDSi Project and the Immunization Information Systems Support Branch, see Clinical Decision Support for Immunization (CDSi).

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