HLN is dedicated to the development, improvement, promulgation, and use of open source solutions, especially in the public health community. and subscribe to the open source definition developed by the open source Initiative (OSI). We believe that open source is compelling, as described in the following SWOT analysis



  • No license fee to use
  • No loss of access to source code if developer stops work or ceases operations
  • Freedom to make/share changes
  • Transparency in governance
  • More transparency in product governance as open source development usually involves more clearly disclosed priorities and decision-making processes
  • Enables modular system deployment as interfaces are themselves open
  • Participative development allows many eyes to scan source code for possible errors or security exposures

  • Risk of detrimental source code “forking” increases as anyone with access to the source code can make changes that may be inconsistent with the original product
  • Burden of enhancements may fall to individual users/organizations
  • as there may be no central owner to perform or even coordinate this work
  • Software support may be harder to acquire as there may be no central owner to perform or even coordinate this work
  • Security patches may be slow to reach users as responsibility for updates may be more diffuse than proprietary software

  • Collaborative development can reduce cost of enhancements and support
  • Commercial vendors often provide solid support even for products they do not own
  • More modular public health systems might enable more open source component use

  • Cloud-based services offering open source product access for a fee effectively make these products behave as proprietary solutions often with no contribution back to the open source community
  • Public health community will not financially support product development
  • Public health community expects open source market to behave like commercial market by providing functional improvements to software without charge
  • Commercial vendor reactions to encroachment of open source on its market is hard to predict

Initiatives and Activities

HLN has extensive experience using, developing and supporting open source technologies, in our IIS work as well as past work in academia and academic-based research.

  • HLN made a major investment in the development of open source tools focused on clinical decision support, utilizing a common framework, including:
    • The Vaccine Provider Agreement System (VPAS), an open source solution to support CDC COVID-19 vaccination program provider agreement requirements. To help the New York City Citywide Immunization Registry (CIR), and now West Virginia meet the CDC COVID-19 Vaccination Program Provider Agreement requirements, HLN Consulting developed the Vaccine Provider Agreement System (VPAS). All access to VPAS is controlled via the use of Magic Links which are customized URLs with embedded tokens that are tied to a specific email address. This is also referred to as Passwordless Authentication. The process begins when VPAS sends an email invitation to a facility staff member containing a unique link that permits that user, and only that user, to login to VPAS. The form can be completed, reviewed, and edited before it is signed and submitted for approval. An extract of the Approved form in the CDC-specified file format can be generated and downloaded.  The entire VPAS database for subsequent importing into other Awardee systems.
    • The ICE Immunization Calculation Engine, a service-oriented, standards-based immunization forecasting software system that evaluates a patient’s immunization history and generates the appropriate immunization recommendations. ICE can be deployed in diverse technical environments and is designed to easily integrate with third party clinical systems (IIS, EHRs, PHRs, analytics) through its standards-based web service. The ICE software distribution includes web-based GUI tools that enable subject matter experts to manage the immunization algorithm rules and terminology, and to manage and execute a set of fully automated tests, all without the intervention of software developers. The ICE software system, including the supporting tools, does not depend on any commercial software and has been publicly released under an open source license. ICE has been implemented as a clinical module within OpenCDS, a software framework that provides developers with a set of standards-based clinical decision support (CDS) resources designed to enable CDS at scale.
    • The Reportable Condition Knowledge Management System (RCKMS), which contains a standards-based web services interface which allows EHR systems to submit initial electronic case reports and evaluate them for reportability to a jurisdiction as a decision support service (see Public Health Case Reporting). To support the service, the system includes an online authoring tool which supports terminology management, reporting specifications and rule maintenance, and a human readable report of reporting specifications. This authoring tool allows jurisdictions to define their own decision support rules for reportability through an easy-to-use web interface. This project is in conjunction with the Council of State and Territorial Epidemiologists (CSTE) and the Centers for Disease Control and Prevention (CDC).
    • Decision Support for Data Segmentation (DS2), prototype software that utilizes SHARPS logoOpenCDS, an open source Clinical Decision Support (CDS) framework, to identify and redact selected conditions from clinical summary documents in an HIE environment. The DS2 software includes a suite of related tools for creating, importing, and editing Continuity of Care (CCD) documents; testing redacted CCDs; and converting CCDs to Virtual Medical Record (vMR) format. The software also includes a web-based “inference analyzer” for visualizing the effectiveness and the impact of probabilistic redaction. This project was conducted in conjunction with the Strategic Health IT Advanced Research Projects on Security (SHARPS).
  • Our Immunization Information System (IIS) deployments in NYC and RI are both supported on Linux and incorporate various open source components, including the HAPI HL7 parser.
  • We work collaboratively with Choicemaker, LLC supporting the Choicemaker probabilistic matching engine that is also an open source product and in use in the New York City Citywide Immunization Registry (CIR). Choicemaker software “mimics” human intuition by comparing two records, testing a set of conditions in the data (which it calls “clues”), and develops a probability score that the two records are for the same person. Different clues receive different weights by the model designers in conjunction with a software-assisted “training” process whereby through machine learning the Choicemaker software “learns” the optimum weights based on normative data supplied to the algorithm.
  • HLN is currently working with NYC to remove all commercial dependencies on CIR software products in preparation for the entire system being placed by NYC in the open source community (centered largely on a migration from Oracle to PostgreSQL, an open source, production-level relational database management system).

This dedication to leverage of investments and the sharing of software make HLN the only company to be positioned for the future of where public health systems development needs to take place: modular, shareable components that can be used by many projects regardless of the “base” software they might have deployed.


HLN believes in a number of strategies for public health especially, including:

  • Begin (or continue) to move public health systems to be more modular and to implement a service-oriented approach (SOA)
  • Leverage widely-used open source products where feasible (e.g., Linux, PostgreSQL, HAPI, Mirth)
  • Jointly develop/support more specialized products when necessary (e.g., decision support tool, quality assurance tools, person matching tools)
  • Look beyond public health community for collaboration (e.g., EHRs, PHRs)
  • Encourage one organization to maintain stewardship over and support each product to prevent “detrimental” forking
  • Recognize and manage any turbulence this may cause in the commercial product marketplace