2026 ICD-10-CM Diagnosis Code Z28.81Immunization not carried out due to patient having had the disease

ICD-10-CM Codes›Z00–Z99›Z20-Z29›Z28

ICD-10-CM Z28.81
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z28.81 is a billable ICD-10-CM diagnosis code for immunization not carried out due to patient having had the disease. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under No immunization or underimmunization.

Code Identity

ICD-10-CM Code
Z28.81
Billable Status
Yes — Valid for Submission
Code Describes
Immunization not carried out due to patient having had the disease
Short Description
Immuniz not crd out due to patient having had the disease
Parent Code
Z28.8
Immunization not carried out for other reason

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ20-Z29Persons with potential health hazards related to communicable diseases
CategoryZ28Immunization not carried out and underimmunization status
This CodeZ28.81Immunization not carried out due to patient having had the disease

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z28.81.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Present on Admission (POA)Billing

Z28.81 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Immunization
      • not done (not carried out)
        • because (of)
          • patient had disease being vaccinated against

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR FAC017
No immunization or underimmunization
Default principal diagnosis: inpatient No · outpatient Yes

Convert Z28.81 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
V64.08 No vaccin-prev disease
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Z28.81Overview

Is Z28.81 (Immunization not carried out for other reason) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report immunization not carried out due to patient having had the disease on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can Z28.81 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because immunization not carried out due to patient having had the disease describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Is Z28.81 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for immunization not carried out due to patient having had the disease on inpatient claims.

What is the ICD-9 equivalent of Z28.81?

Under the General Equivalence Mappings, immunization not carried out due to patient having had the disease converts to ICD-9-CM V64.08 (no vaccin-prev disease). The mapping is a direct match.