Immunization not carried out and underimmunization status
In Persons with potential health hazards related to communicable diseases (Z20-Z29), chapter 21: Factors Influencing Health Status and Contact with Health Services
17 billable codes under Z28: none are a CC or MCC; none map to an HCC.
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Instructional notes
Includes: conditions that are coded here
- vaccination not carried out
Code also: add a code for this too, order depends on the encounter
- if applicable, encounter for immunization safety counseling (Z71.85)
Official coding guidelines
From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.
Covers when and how to use Z codes (Z00-Z99) for encounters and supplementary information, including contact, status, history, screening, aftercare, exams, and social determinants of health.
All codes under Z28
Z28 can't be used on a claim. Pick a billable code below; grey headings group them.
- Z28.0Immunization not carried out because of contraindication
- Z28.01Immunization not carried out because of acute illness of patient
- Z28.02Immunization not carried out because of chronic illness or condition of patient
- Z28.03Immunization not carried out because of immune compromised state of patient
- Z28.04Immunization not carried out because of patient allergy to vaccine or component
- Z28.09Immunization not carried out because of other contraindication
- Z28.1Immunization not carried out because of patient decision for reasons of belief or group pressure
- Z28.2Immunization not carried out because of patient decision for other and unspecified reason
- Z28.20Immunization not carried out because of patient decision for unspecified reason
- Z28.21Immunization not carried out because of patient refusal
- Z28.29Immunization not carried out because of patient decision for other reason
- Z28.3Underimmunization status
- Z28.31Underimmunization for COVID-19 status
- Z28.310Unvaccinated for COVID-19
- Z28.311Partially vaccinated for COVID-19
- Z28.39Other underimmunization status
- Z28.8Immunization not carried out for other reason
- Z28.81Immunization not carried out due to patient having had the disease
- Z28.82Immunization not carried out because of caregiver refusal
- Z28.83Immunization not carried out due to unavailability of vaccine
- Z28.89Immunization not carried out for other reason
- Z28.9Immunization not carried out for unspecified reason
Z28 MS-DRGs
As the principal diagnosis, the billable codes under Z28 group to MS-DRG 951 or 795 (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.
- DRG 951 Other Factors Influencing Health Status (17 of 17 codes)
- DRG 795 Normal Newborn (14 of 17 codes)
Other codes that refer to Z28
Notes on these codes point to Z28.
- Z71.85 Code Also: if applicable, immunization not carried out (Z28.-)
Code history
Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.