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ICD-10/Z28.310

Z28.310 ICD-10-CM Code: Unvaccinated for COVID-19

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Inpatient Payment Groups (MS-DRG)

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43.0 (FY2026), Appendix B.

  • MS-DRG 951 — OTHER FACTORS INFLUENCING HEALTH STATUS (MDC 23)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Code Set: Valid FY2026 and FY2027. FY2026 took effect October 1, 2025.

Official Registry Overview & Definition

Unvaccinated for COVID-19 is a billable ICD-10-CM diagnosis code (Z28.310).

Official Tabular Instructional Notes

Sequencing, inclusion, and exclusion notes published for Z28.310 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-)

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Z28.310 in its code family, with their registry titles.

  • 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
  • Z28.31 — Underimmunization for COVID-19 status
  • 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
  • Z28.82 — Immunization not carried out because of caregiver refusal

View all codes in the Z28 family

Indexed Clinical Terms (5)

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code.

  • COVID-19, unvaccinated (for)
  • Status (post), underimmunization, COVID-19, unvaccinated (for)
  • Underimmunization status, COVID-19, unvaccinated (for)
  • Unimmunized, for COVID-19
  • Unvaccinated, for COVID-19