2027 ICD-10-CM Diagnosis Code Z28.21Immunization not carried out because of patient refusal

ICD-10-CM Codes›Z00–Z99›Z20-Z29›Z28

ICD-10-CM Z28.21
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Z28.21 is a billable ICD-10-CM diagnosis code for immunization not carried out because of patient refusal. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 795, 951. 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
Z28.21
Billable Status
Yes — Valid for Submission
Code Describes
Immunization not carried out because of patient refusal
Short Description
Immunization not carried out because of patient refusal
Same as the full description in the CMS dataset.
Parent Code
Z28.2
Immunization not carried out because of patient decision for other and unspecified 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 CodeZ28.21Immunization not carried out because of patient refusal

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z28.21.

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

Z28.21 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Persons with potential health hazards related to communicable diseases (Z20-Z29).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • BCG vaccination declined
  • Booster meningitis B vaccination declined
  • First meningitis B vaccination declined
  • Hepatitis A vaccination declined
  • Hepatitis B immunization declined
  • Human papillomavirus vaccination declined
  • Human respiratory syncytial virus vaccination declined
  • Inactivated whole SARS-CoV-2 antigen vaccine declined
  • Influenza A virus subtype H1N1 vaccination declined
  • Influenza vaccination declined
  • Measles, mumps and rubella vaccination declined
  • Meningitis B vaccination declined
  • Meningitis C immunization declined
  • Meningococcal vaccination declined
  • Pertussis vaccination declined
  • Pneumococcal vaccination declined
  • SARS-CoV-2 antigen vaccine declined
  • SARS-CoV-2 DNA plasmid encoding spike protein vaccine declined
  • SARS-CoV-2 mRNA vaccine declined
  • SARS-CoV-2 non-replicating viral vector vaccine declined
  • SARS-CoV-2 recombinant spike protein antigen vaccine declined
  • SARS-CoV-2 vaccination declined
  • SARS-CoV-2 virus-like particle antigen vaccine declined
  • Second dose of inactivated whole SARS-CoV-2 antigen vaccine declined
  • Second dose of SARS-CoV-2 mRNA vaccine declined
  • Second dose of SARS-CoV-2 non-replicating viral vector vaccine declined
  • Second dose of SARS-CoV-2 recombinant spike protein antigen vaccine declined
  • Second dose of SARS-CoV-2 virus-like particle antigen vaccine declined
  • Second meningitis B vaccination declined
  • Tetanus vaccination declined by patient
  • Vaccination declined
  • Vaccination hesitancy by parent
  • Vaccination hesitancy by patient
  • Vaccine declined by patient
  • Varicella zoster vaccination declined by patient

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Z28.21: its own notes plus those printed at Z28 and Chapter 21. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Z28 Immunization not carried out and underimmunization status applies to 17 codes
  • vaccination not carried out

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From Z28 Immunization not carried out and underimmunization status applies to 17 codes
  • if applicable, encounter for immunization safety counseling (Z71.85)

Notes

General instructions on how these codes are used.

From Chapter 21 (Z00-Z99) Factors influencing health status and contact with health services applies to 1,425 codes
  • Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
  • (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
  • (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name Z28.21, its category, or a range that includes it.

Use Additional Code 1

These codes say to use an additional code from the note, and Z28.21 is one of the codes named.

  • Z28.3 Underimmunization status
    immunization not carried out because of patient decision for other and unspecified reason (Z28.2-) names Z28.2-, which includes this code

Code Also 1

These codes say Z28.21 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • Z71.85 Encounter for immunization safety counseling
    if applicable, immunization not carried out (Z28.-) names Z28.-, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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 Z28.21 to ICD-9-CMHistory

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

ICD-9-CM
V64.06 No vaccination-pt refuse
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Z28.21Overview

What is the ICD-10 code for immunization not carried out because of patient refusal?

The ICD-10-CM code for immunization not carried out because of patient refusal is Z28.21 (sometimes written as Z2821). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Z28.21 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report immunization not carried out because of patient refusal on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Z28.21 group to?

On inpatient claims, immunization not carried out because of patient refusal maps to MS-DRG 951, 795, with relative weights from 0.2022 to 0.5574 depending on complications. Higher weights mean higher Medicare reimbursement.

Can Z28.21 be a principal diagnosis?

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

Is Z28.21 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 because of patient refusal on inpatient claims. The code appears in the Persons with potential health hazards related to communicable diseases (Z20-Z29) range of the CMS exempt list.