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ICD-10-CM 2027 diagnosis code

Z28.310Unvaccinated for COVID-19

✓ Billable / specificPOA exemptNot a principal dx

Z28.310 is a valid, billable ICD-10-CM code for unvaccinated for covid-19. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code last changed in FY2022 (effective October 1, 2021). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About Z28.310

Z28.310 is the ICD-10-CM diagnosis code for Unvaccinated for COVID-19. It belongs to category Z28 (immunization not carried out and underimmunization status), block Z20-Z29 (persons with potential health hazards related to communicable diseases) and chapter 21 (factors influencing health status and contact with health services). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within Z28.31 (underimmunization for COVID-19 status), Z28.310 is specifically for Unvaccinated for COVID-19. Related codes cover Partially vaccinated for COVID-19 (Z28.311).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 951 (Other Factors Influencing Health Status, relative weight 0.5577), in MDC 23 (Factors Influencing Health Status and Other Contacts with Health Services), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.

It is exempt from present-on-admission (POA) reporting, so no POA indicator is required.

It was added in FY2022, effective October 1, 2021.

Notes that apply from higher levels

Instructions written at a parent level also apply to Z28.310.

› From Z28.31 Underimmunization for COVID-19 status
Note
  • These codes should not be used for individuals who are not eligible for the COVID-19 vaccines, as determined by the healthcare provider.
› From Z28.3 Underimmunization status
Use additional code
  • 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-)
› From Z28 Immunization not carried out and underimmunization status
Includes
  • vaccination not carried out
Code also
  • , if applicable, encounter for immunization safety counseling (Z71.85)

Broader instructions also apply from Chapter 21: Factors influencing health status and contact with health services.

Alphabetic index entries

5 entries

Terms in the official ICD-10-CM index that lead to Z28.310.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

MDC 23 · Factors Influencing Health Status and Other Contacts with Health Services

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2022 (effective 10/1/2021): Added
  • No changes since FY2022.

Common questions about Z28.310

Is Z28.310 billable?

Yes. Z28.310 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can Z28.310 be used as a principal diagnosis?

No. It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.

Is Z28.310 a CC or MCC?

No. Z28.310 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does Z28.310 group to?

Z28.310 is used in the MS-DRG v44.0 logic for MS-DRG 951 (Other Factors Influencing Health Status). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.