Clinical Decision Support

for Immunization (CDSi)
The federal Advisory Committee on Immunization 

Practices (ACIP) provides expert advice and 

guidance on the use of vaccines and related 

agents for the control of vaccine-preventable 

disease in the United States. ACIP recommendations include the age for vaccine administration, 

number of doses, dosing interval, special 

indications for at-risk individuals, and precautions 

and contraindications. 

The Challenge:

Updating CDS Engines

As ACIP recommendations are published, 

evaluation and forecasting engines—known as 

Clinical Decision Support (CDS) engines—need to 

be updated to determine recommended 

immunizations for a patient and deliver those 

recommendations to the healthcare provider.

Translating the ACIP recommendations’ clinical

language into technical logic that can be 

processed with CDS engines, however, is a 

time-consuming and complex process that occurs 

mostly independently within the different Health 

Information Systems (e.g., Immunization 

Information Systems [IIS], Electronic Health Records 

[EHRs], and [HIS] Health Information Exchanges).

The outcome? CDS engine outputs that often vary 

and do not always match the expectations of 

clinical subject matter experts (SMEs)

The Solution:

Easing the Process

of Updating CDS Engines

Funded by the Immunization Information System 

Support Branch at the Centers for Disease Control 

and Prevention (CDC), the Clinical Decision 

Support for Immunization (CDSi) project was 

established to harmonize CDS engine outputs by 

developing a technical framework and resources 

focusing on the following goals:

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Improving the process of updating CDS logic 

with new and/or changed ACIP 

recommendations 

Increasing the accuracy and consistency of 

immunization evaluation and forecasting 

Improving the ease of developing and 

maintaining immunization CDS products

The CDSi project was executed in two phases: PHASE 1

Objective Panel

PHASE 2

Develop CDSi resources such as a Logic

Specification, Supporting Data, and Test 

Cases for vaccine groups routinely

recommended by ACIP for healthy

children from birth through 18 years 

SMEs and expert reviewers from the CDC Public

Health Informatics andTechnology Program Office,

American Immunization Registry Association,

Indian Health Service, EHR vendors, programs

and vendors, and academic institutions

Expand the project’s scope to include

adult vaccines and special-risk indications 

Phase 1 representatives as well as representatives

from the Veterans Administration, American

College of Physicians, and American Academy

of Family Practitioners
d 

The Scope

The target audience for the CDSi project includes business and/or technical implementers of 

immunization CDS engines. These implementers may support any system with an immunization 

evaluation and forecasting engine including but not limited to IIS and EHRs.

The current scope of the project includes those vaccine groups routinely recommended by ACIP for 

healthy individuals from birth through age 65+ years, as well as those who have risk indications relate

to underlying medical conditions:

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Diphtheria, Tetanus, and Pertussis

(DTaP, Tdap, Td)

Hepatitis A

Hepatitis B

Haemophilus influenzae type B (Hib)

Human papillomavirus (HPV)

Influenza (Flu)

Japanese Encephalitis

Measles, Mumps, Rubella (MMR)

Meningococcal ACWY conjugate

vaccine (MCV)

Meningococcal B

Pneumococcal

Poliomyelitis

Rabies

Rotavirus

Typhoid

Varicella

Yellow Fever

Zoster

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Current ACIP recommendations with

clarifications

Underlying conditions related to contraindications or risk indications listed in the

General Recommendations and other ACIP

publications

The 4-day grace period

The catch-up schedule

Aged-based adult recommendations

Travel vaccines

Underlying conditions related

to precautions and special indications

for at-risk individuals

High/increased/special risk series

(e.g., Hib past 5 years)

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Additional items in scope include: 
The Strategy

The complexity of the problem and the project goals influenced the design strategy. The 

guiding principles were to: 

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Separate the complex problem into simpler, more focused parts: the data, the algorithm, and the

framework that pulls the data and algorithm together

Emphasize “universal” functionality across IIS implementations instead of more detailed,

implementation-specific engineering requirements for local needs and technical

environments.

Utilize a variety of mechanisms (e.g., business rules, decision tables, process models, and a domain

model) to document the specification, providing a concise, unambiguous, computable description

of the functionality required.

Develop a testing methodology that utilizes test cases and expected results to validate CDS

algorithms against the Logic Specification.

The design strategy culminated in the creation of three resources: the Logic Specification, 

Supporting Data, and Test Cases.
Logic Specification

Supporting Data

Test Cases

Updated

CDS Engines

IIS – EHR – HIE

ACIP

Recommendations

The CDSi resources translate clinical

recommendations into technical information

Training Materials – Brochure

– Quick Guides

– Practice Exercise

– Quiz

– Videos

The complete suite of CDSi resources comprises:

Logic Specification Supporting Data Test Cases

– Vocabulary

– Business Rules

– Decision Tables

– Processing Definitions

– Domain Model

– Excel Format

– XML Format

– Release Notes

– Excel Format

The Resources

Logic Specification - Documents the logic for applying ACIP business rules to CDS engines required 

to evaluate and forecast based on a patient’s immunization history and the Supporting Data

Supporting Data - Describes, by antigen, the attributes (e.g., minimum age, earliest recommended 

age, and preferable vaccine type) necessary and specific values (e.g., schedule-specific, antigen

series-specific, and dose-specific) required to support evaluation and forecasting as described by 

the Logic Specification

Test Cases – Provide a representative set of scenarios and expected outcomes that can be processed 

against an immunization evaluation and forecasting engine to validate or test its algorithm against 

the Logic Specification and Supporting Data
The CDSi resources provide a single, authoritative, implementation-neutral foundation for developing 

and maintaining CDS engines to ensure patients receive “the right immunization at the right time.” 

Using these CDSi resources:

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Makes it easier to develop and maintain immunization evaluation and forecasting products

Ensures a patient’s immunization status is current, accurate, consistent, and readily available

Increases the accuracy and consistency of immunization evaluation and forecasting

Improves the timeliness of accommodating new and updated ACIP recommendations

The Result:

Ensuring the Right Immunization at the Right Time
FAQs

How are the CDSi resources being used?

Members of the IIS community are using the CDSi resources to support updates to their forecasting and 

evaluation engines and even build engines from scratch. Community members are also:

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Consulting the Supporting Data for clarification when rules are complex and clinical SME team

members cannot agree

Testing immunization forecasting algorithms against CDSi Test Cases to ensure their

recommendations or evaluations align

Referencing the Supporting Data as industry standards to help answer clients’ questions about

particular forecasts or recommendations

What will happen when ACIP makes recommendation changes?

Each time ACIP updates its recommendations, a team designated to maintain the resources will make 

the appropriate updates. Subsequently, communications will be disseminated to make the HIS 

community aware of the changes

How can I obtain support?

The CDSi resources and training materials can be found on the CDC’s Immunization Information System 

Support Branch website at: www.cdc.gov/vaccines/programs/iis/cdsi.html

You can also obtain support by emailing: nipinfo@cdc.gov
Contact Information

Stuart Myerburg

Health Scientist, Informatics

Centers for Disease Control and Prevention

Immunization Information Systems Support Branch

1600 Clifton Road NE, Building 24

Mailstop A-19

Atlanta, GA 30333

NIPInfo@cdc.gov

Eric Larson

Northrop Grumman Contractor

Centers for Disease Control and Prevention

Immunization Information Systems Support Branch

1600 Clifton Road NE, Building 24

Mailstop A-19

Atlanta, GA 30333

NIPInfo@cdc.gov