Z28.311 Partially vaccinated for COVID-19

✓ Billable ICD-10-CM 2026
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The ICD-10-CM code for Partially vaccinated for COVID-19 is Z28.311 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Section
Z20-Z29: Persons with potential health hazards related to communicable diseases (Z20-Z29)
Category Z28
23 codes (17 billable)
FY2026 Status
Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to Z28.311:

  • COVID-19 › partially vaccinated (for)
  • Vaccination (prophylactic) › partial › for COVID-19
  • Immunization › partial › for COVID-19
  • Underimmunization status › COVID-19 › partially vaccinated (for)
  • Status (post) › underimmunization › COVID-19 › partially vaccinated (for)

U.S. Hospital Utilization

  • An estimated 46,455 U.S. inpatient stays in 2023 included Z28.311 among the documented diagnoses.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Underimmunization status: Z28.310 unvaccinated; Z28.311 partial

(n) Underimmunization for COVID-19 Status Code Z28.310, Unvaccinated for COVID-19, may be assigned when the patient has not received a COVID-19 vaccine of any type. Code Z28.311, Partially vaccinated for COVID-19, may be assigned when the patient has been partially vaccinated for COVID-19 as per the recommendations of the Centers for Disease Control and Prevention (CDC) in place at the time of the encounter. For information, visit the CDC’s website https://www.cdc.gov/covidschedule.

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.1.g.1.n
List of miscellaneous Z codes with exceptions/notes

Miscellaneous Z codes/subcategories/categories: Z28 Immunization not carried out Except: Z28.3-, Underimmunization status Z29 Encounter for other prophylactic measures Z40 Encounter for prophylactic surgery Z41 Encounter for procedures for purposes other than remedying health state Except: Z41.9, Encounter for procedure for purposes other than remedying health state, unspecified Z53 Persons encountering health services for specific procedures and treatment, not carried out Z72 Problems related to lifestyle Note: These codes should be assigned only when the documentation specifies that the patient has an associated problem Z73 Problems related to life management difficulty Note: These codes should be assigned only when the documentation specifies that the patient has an associated problem. Z74 Problems related to care provider dependency Except: Z74.01, Bed confinement status Z75 Problems related to medical facilities and other health care Z76.0 Encounter for issue of repeat prescription

— ICD-10-CM Official Guidelines for Coding and Reporting, FY2026, Section I.C.21.c.13.c

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

Related Codes

Parent Code

Z28 Immunization not carried out and underimmunization status

Related Codes in Z28

Z28 Immunization not carried out and underimmunization status Z28.0 Immunization not carried out because of contraindication Z28.01 Immunization not carried out because of acute illness of patient Z28.02 Immunization not carried out because of chronic illness or condition of patient Z28.03 Immunization not carried out because of immune compromised state of patient Z28.04 Immunization not carried out because of patient allergy to vaccine or component Z28.09 Immunization not carried out because of other contraindication Z28.1 Immunization not carried out because of patient decision for reasons of belief or group pressure 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 Z28.31 Underimmunization for COVID-19 status Z28.310 Unvaccinated 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 Z28.83 Immunization not carried out due to unavailability of vaccine
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Reviewed by Prajwal Shrestha, CPC, CRC
Certified Professional Coder (CPC) and Certified Risk Adjustment Coder (CRC) · AAPC Member ID 01997614 · About · Editorial policy · Content last reviewed: 2025-10-01

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