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Z28.31 ICD-10-CM Code: Underimmunization for COVID-19 status

Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.

Official Registry Overview & Definition

Underimmunization for COVID-19 status is a non-billable ICD-10-CM category code (Z28.31). A more specific billable subcode must be selected for claims submission.

Official Tabular Instructional Notes

Sequencing, inclusion, and exclusion notes published for Z28.31 in the official ICD-10-CM tabular list.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • vaccination not carried out

Code Also

Additional codes that may be required to fully describe the encounter.

  • Code also, if applicable, encounter for immunization safety counseling (Z71.85)

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code, if applicable, to identify:
  • immunization not carried out because of contraindication (Z28.0-)
  • immunization not carried out because of patient decision for other and unspecified reason (Z28.2-)
  • immunization not carried out because of patient decision for reasons of belief or group pressure (Z28.1)
  • immunization not carried out for other reason (Z28.8-)

Change history

  • FY2022 — 2021-10-01
    Added to the code set
    Underimmunization for COVID-19 status
    FY2022 changes

Verify Before Coding

  • Not billable as written — a more specific code is required: Z28.310, Z28.311.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim.

Contextual Map

Every relationship of Z28.31 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Hierarchy

  • Z00-Z99 — Chapter 21: Factors Influencing Health Status and Contact with Health Services (Z00-Z99) (Z00-Z99) [Hierarchy]
  • Z20-Z29 — Persons with potential health hazards related to communicable diseases [Hierarchy]

Referenced by Code Also instructions

  • Z71.85 — Encounter for immunization safety counseling [Code Also](via Z28.-): “, if applicable, immunization not carried out (Z28.-)” · check together

Nearest codes (22)

  • Z28 — Immunization not carried out and underimmunization status [Sibling]
  • Z28.0 — Immunization not carried out because of contraindication [Sibling]
  • Z28.01 — Immunization not carried out because of acute illness of patient [Sibling]
  • Z28.02 — Immunization not carried out because of chronic illness or condition of patient [Sibling]
  • Z28.03 — Immunization not carried out because of immune compromised state of patient [Sibling]
  • Z28.04 — Immunization not carried out because of patient allergy to vaccine or component [Sibling]
  • Z28.09 — Immunization not carried out because of other contraindication [Sibling]
  • Z28.1 — Immunization not carried out because of patient decision for reasons of belief or group pressure [Sibling]
  • and 14 more

Change history

  • FY2022 — Added to the code set [Change history]

Referenced by Other Codes

Official ICD-10-CM tabular notes on other codes that name Z28.31 or its code family.

1 Code Also instructions: Z71.85 (via Z28.-).

Frequently Asked Questions (FAQ) & Clinical Guidance

Can Z28.31 be billed directly?

No. Z28.31 (Underimmunization for COVID-19 status) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Z28.31 in its code family, with their registry titles.

  • Z28.2 — Immunization not carried out because of patient decision for other and unspecified reason
  • Z28.20 — Immunization not carried out because of patient decision for unspecified reason
  • Z28.21 — Immunization not carried out because of patient refusal
  • Z28.29 — Immunization not carried out because of patient decision for other reason
  • Z28.3 — Underimmunization status
  • Z28.310 — Unvaccinated for COVID-19
  • Z28.311 — Partially vaccinated for COVID-19
  • Z28.39 — Other underimmunization status
  • Z28.8 — Immunization not carried out for other reason
  • Z28.81 — Immunization not carried out due to patient having had the disease

View all codes in the Z28 family