Z28.310 — Unvaccinated for COVID-19
Is Z28.310 billable?
Yes — Z28.310 is billable for FY2027. Z28.310 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. Z28.310 may be submitted for encounters from October 1, 2026 through September 30, 2027.
Z28.310 at a glance
| Code | Z28.310 |
|---|---|
| Description | Unvaccinated for COVID-19 |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
What Medicare edits apply to Z28.310?
The Medicare Code Editor screens inpatient claims before they are grouped. These edits name Z28.310 directly.
CMS will reject this code as the principal diagnosis on an inpatient claim. It describes something other than the condition chiefly responsible for the admission.
Which MS-DRGs does Z28.310 group to?
Z28.310 sits in MDC 23 and helps define the logic of 1 MS-DRG (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 951Other Factors Influencing Health Statusmedical
How is Z28.310 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to Z28.310. They show the wording a clinician may have documented, which often differs from the Tabular description.
- COVID-19 › unvaccinated
- Unimmunized › for COVID-19
- Unvaccinated › for COVID-19
- Underimmunization status › COVID-19 › unvaccinated
- Status › underimmunization › COVID-19 › unvaccinated (post)
Use additional code — inherited from Z28.3
Report an additional code alongside Z28.310 to fully describe the condition. Z28.310 is sequenced first.
- 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-)
Code also — inherited from Z28
Two codes may be needed to describe the condition fully. Whether Z28.310 is sequenced first depends on the reason for the encounter.
- , if applicable, encounter for immunization safety counseling (Z71.85)
How long has Z28.310 existed?
Z28.310 first appears in FY2023.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.