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What is ICE?

The Immunization Calculation Engine (ICE) is a free, open-source immunization forecasting software system. The core component of ICE is the ICE Web Service, which evaluates a patient's immunization history and generates the appropriate immunization recommendations for the patient. The ICE Web Service runs in OpenCDS which is a third-party platform that may be used to build decision support services for any clinical domain.

ICE comes initially configured with a default immunization schedule that supports all routine childhood, adolescent, and adult immunizations - based on the recommendations of the Advisory Committee on Immunization Practices (ACIP).

The ICE software system has been developed and configured by a collaborative partnership of public health experts and information technology experts from the organizations listed below and has been released under a standard open-source license:

New York City Department of Health and Mental Hygiene, Citywide Immunization Registry (CIR)
HLN Consulting, LLC
Alabama Department of Public Health (ADPH)
The OpenCDS collaboration spearheaded by Dr. Kensaku Kawamoto and colleagues at the University of Utah, Department of Biomedical Informatics.

Due to its standards-based Web Service interface, its Java-based implementation, and its complete lack of dependence on any commercial software, ICE can be deployed in diverse technical environments and easily integrates with third party clinical systems such as Immunization Information Systems (IIS), Electronic Health Record Systems (EHR-S), and Health Information Exchanges (HIEs).

Clinical systems utilize the ICE Web Service by passing a Virtual Medical Record (vMR) to its Web Service which adheres to the Decision Support Service (DSS) standard. In response, ICE utilizes its immunization rules and the data in the vMR, such as the patient’s date of birth, gender, immunization history, and disease indicators, to evaluate and return the validity of each immunization in the patient’s history along with one or more evaluation reasons. It also returns a recommendation for each vaccine group along with one or more recommendation reasons. ICE’s Web Service architecture scales to support simultaneous real-time processing of many patients submitted by one or more systems. It can also service requests for multiple immunization schedules. For example, a single ICE deployment could enforce one immunization schedule utilized by an IIS, another immunization schedule used by multiple EHR-S, and a third immunization schedule utilized by a school health system.

Current News

February 18, 2025 - New Release of ICE - Version 2.45.2

A new release of ICE is available - Download the latest ICE release now.
Version 2.45.2 fixes an issue discovered in v2.45.1 where the HPV minimum age was changed from 9 years to 11 years. This was an inadvertent change in the files included in the final v2.45.1 release. Version 2.45.2 resets the HPV minimum age to 9 years.
For information about what is included in version 2.45, please see the News entry below and the Release Notes.
Not sure which version of ICE you're currently using? View the README.HISTORY file included with each zipfile distribution or pull the version dynamically at the following endpoint: http(s)://<host>:<port>/path/to/opencds-decision-support-service/version.
Our sincere apologies for this error. If you have any questions, comments, or suggestions, please reach out to us at ice@hln.com.

February 17, 2025 - New Release of ICE - Version 2.45.1

A new release of ICE is available - Download the latest ICE release now.
Version 2.45.1 includes the following updates:
- COVID-19: Added support for the 23-24 season additional dose for patients 65 years and older; added support for the 24-25 season recommendations, including the additional dose for patients 65 years and older. Several updates to ensure alignment with the latest recommendations.
- Hepatitis B: Series selection implementation updates to ensure the appropriate series is selected in certain circumstances.
- Hib: Added CVX 132 to the implementation files for the Hib 4-dose Series (no wiki rule change).
- RSV: Updated the display name for CVX 307 in the configuration files (no wiki rule changes). Updated the rules to support validation of infant RSV CVX codes starting on 8/3/2023 and to support validation of adult and otherwise unspecified RSV CVX codes starting on 6/21/2023. Updated the supplemental text to remove special characters (apostrophe and en dash).
- Zoster: Updated the implementation of the minimum interval between a CVX 121 or CVX 188 to a CVX 187 to 56 days rather than 28 days, to align with the wiki rules.
- Additional Updates: Addressed an issue with supplemental text, where, in some circumstances, supplemental text associated with one vaccine group appeared in the forecast output for a different vaccine group.
- The ICE Implementation Guide Codes sheet has been updated to reflect the changes in the RSV supplemental text.
- Please see the Release Notes for additional details.
Not sure which version of ICE you're currently using? View the README.HISTORY file included with each zipfile distribution or pull the version dynamically at the following endpoint: http(s)://<host>:<port>/path/to/opencds-decision-support-service/version.
Forthcoming ICE releases: Upcoming ICE release will address changes in the Pneumococcal and Meningococcal B vaccine groups.
If you have any questions, comments, or suggestions, please reach out to us at ice@hln.com.

The Importance of Upgrading After Each ICE Release

With each new release, we strongly recommend that all users and service providers update their running instances of ICE as soon as possible to the latest version. Each new release contains important forecaster business logic updates and fixes.

ICE Code Systems and Codes Now Available in Google Sheets

The ICE code systems and codes are now accessible in Google Sheets as an added convenience. These are the codes as those in the Implementation Guide. The codes will continue be updated in both the places.
The Google Sheet is available here.

Configuration Notes

As of release 1.24.1, the ICE service is configured with the output_supplemental_text option in the properties file set to enabled by default.

As of release 1.16.1, the ICE service is configured by default to return the earliest and overdue dates in addition to the recommendation date. In prior releases, the default configuration was to return only the recommendation date for the forecast.
- If your application has not been configured to display the earliest and/or overdue dates, we recommend turning this feature off by changing the output_earliest_and_overdue_dates value in the ice.properties file to "N". Failure to do so may result in incorrect interpretation of the recommendation date.
- If you are interested in returning the earliest date or overdue date, please refer to the latest ICE Implementation Guide for details indicating precisely where each of the forecast dates – earliest, recommended, and overdue – are specified in the ICE output, and under what circumstances.

For more information, see the Full List of Archived News...

ICE Recognized as a Digital Public Good

In 2021, the Immunization Calculation Engine (ICE) project was chosen by the Digital Public Goods Alliance as an innovative openly licensed technology and listed in their Digital Public Goods registry. Digital Public Goods have clear documentation, open licenses, and support Sustainable Development Goals, in alignment with the requirements of the Digital Public Goods Standard. Noam Arzt, President of HLN Consulting stated,

"For us, being recognized as a digital public good means expanding the exposure to the ICE open source software and minimizing the barriers to installing and using ICE anywhere in the world." Arzt added that "While ICE rules are currently based on US ACIP recommendations, it can be adapted to include rules based on WHO clinical guidelines or country-specific requirements."

Flexibility is one of the key reasons why HLN chose open source as their development model for ICE. Read the HLN blog and the press release to learn more.

ICE Wins a 2017 Upshot Award from the National Vaccine Program Office (NVPO)

On June 6, 2017, HLN was awarded the 2017 Upshot Award for Excellence in Vaccine Supply, Access, and Use by the National Vaccine Program Office (NVPO) for its ICE Open Source Immunization Forecaster. In the letter of award, Dr. Jewel Mullen, Principal Deputy Assistant Secretary for Health commented that,

"HLN Consulting’s efforts on the Immunization Calculation Engine (ICE) are impressive. This powerful tool-including its open-source nature and seamless integration into clinical workflows-holds great promise for improving clinical decision-support and ultimately vaccination rates. Thank you for daring to innovate, collaborate, and lead in an area that is not only complex, but constantly evolving."

Mike Suralik, one of HLN’s project managers, was on hand to receive the award at the meeting of the National Vaccine Advisory Committee in Washington, DC. HLN is pleased to accept this award on behalf of the ICE project. Read the HLN press release to learn more.

Try Using ICE from Your Web browser

A simple application, called "ICE Client", has been created and made freely available so that anyone can submit sample patient data to the ICE Web Service and see the evaluations and recommendations that the ICE Web Service returns. Try ICE now from your web browser.