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  6. 2024 ICD-10-CM Code Z28.31
Version 2024
Non-Billable Code

2024 ICD-10-CM Diagnosis Code Z28.31

Underimmunization for COVID-19 status

ICD-10-CM Code:
Z28.31
ICD-10 Code for:
Underimmunization for COVID-19 status
Is Billable?
Not Valid for Submission
Code Navigator:

Code Classification

  • Factors influencing health status and contact with health services
    (Z00–Z99)
    • Persons with potential health hazards related to communicable diseases
      (Z20-Z29)
      • Immunization not carried out and underimmunization status
        (Z28)

Z28.31 is a non-specific and non-billable diagnosis code code, consider using a code with a higher level of specificity for a diagnosis of underimmunization for covid-19 status. The code is not specific and is NOT valid for the year 2024 for the submission of HIPAA-covered transactions. Category or Header define the heading of a category of codes that may be further subdivided by the use of 4th, 5th, 6th or 7th characters.

Specific Coding Applicable to Underimmunization for COVID-19 status

Non-specific codes like Z28.31 require more digits to indicate the appropriate level of specificity. Consider using any of the following ICD-10-CM codes with a higher level of specificity when coding for underimmunization for covid-19 status:

  • Use Z28.310 for Unvaccinated for COVID-19 - BILLABLE CODE

  • Use Z28.311 for Partially vaccinated for COVID-19 - BILLABLE CODE

Tabular List of Diseases and Injuries

The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.


  • These codes should not be used for individuals who are not eligible for the COVID-19 vaccines, as determined by the healthcare provider.

Index to Diseases and Injuries References

The following annotation back-references for this diagnosis code are found in the injuries and diseases index. The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10-CM code(s).

Code History

  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023