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Breaking: ICD-10-CM adds Z codes for partially, unvaccinated patients

Starting April 1, you’ll have new ICD-10-CM Z codes to report if you find the patient you are treating is partially vaccinated or unvaccinated for COVID-19.
The CDC has released an updated code set effective April 1, 2022, which includes four new additions under Chapter 21 (Factors influencing health status and contact with health services).
The changes include:
  • New subcategory Z28.31 (Underimmunization for COVID-19 status), and under it, two new patient status codes:
    • Z28.310 (Unvaccinated for COVID-19).
    • Z28.311 (Partially vaccinated for COVID-19).
  • Z29.39 (Other underimmunization status).
Note that “these are not to be reported for individuals who are not eligible for the vaccines, as determined by the provider,” a tabular guideline states.
In addition, you’ll find new code Z28.39 (Other underimmunization status), which may be reported when a patient is delayed or lapsed in getting other non-COVID vaccines.
The code changes, released by the ICD-10-CM Coordination and Maintenance Committee, include tabular and index updates, as well as additions to the ICD-10-CM Official Guidelines for Coding and Reporting.
In the guidelines, the committee explains coding of “Underimmunization for COVID-19 Status”:
“Code Z18.310, Unvaccinated for COVID-19, may be assigned when the patient has not received at least one dose of any COVID-19 vaccine. Code Z28.311, Partially vaccinated for COVID-19, may be assigned when the patient has received at least one dose of a multi-dose COVID-19 vaccine regimen, but has not received the full set of doses necessary to meet the Centers for Disease Control and Prevention (CDC) definition of “fully vaccinated” in place at the time of the encounter. For information, visit the CDC’s website”
(Note: The ICD-10-CM guidelines cite code "Z18.310," which does not exist, but it appears the new code, Z28.310, is intended.)
The ICD-10 Coordination and Maintenance Committee had discussed the April addition at its September meeting, stating that CDC’s National Center for Health Statistics proposed the new undervaccinated status codes because “during the current time of the COVID-19 pandemic, immunizations have provided protection for many people, but there is interest in being able to track people who are not immunized or only partially immunized. At the current time, this is a significant modifiable risk factor for morbidity and mortality, and of interest for clinical reasons, as well as of value for public health.”
Besides the new Z codes, the rest of the April updates include minor edits to a handful of codes’ Tabular instructions, such as changing an Excludes 1 note to an Excludes 2 note.
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