Z28.31 – Underimmunization for COVID-19 status
ICD-10-CM 2027 diagnosis code · Persons with potential health hazards related to communicable diseases
- Code
Z28.31(claims format:Z2831)- Description
- Underimmunization for COVID-19 status
- Billable
- No – use a more specific code below
- Valid for
- Dates of service October 1, 2026 – September 30, 2027 (FY2027)
- Chapter
- 21. Factors influencing health status and contact with health services (Z00-Z99)
- Block
- Z20-Z29 Persons with potential health hazards related to communicable diseases
- Parent codes
- Z28 › Z28.3
Billable codes under Z28.31
Z28.31 is a header code and cannot be used on claims. Choose the most specific code:
Notes for Z28.31
- These codes should not be used for individuals who are not eligible for the COVID-19 vaccines, as determined by the healthcare provider.
Notes inherited from parent codes
Instructional notes at a category or block level apply to every code below it.
Z28 – Immunization not carried out and underimmunization status
- vaccination not carried out
- , if applicable, encounter for immunization safety counseling (Z71.85)
Z28.3 – Underimmunization status
- 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-)
Index terms for Z28.31
Entries in the ICD-10-CM alphabetic index that lead to this code:
Related codes in Z28.3
Frequently asked questions
What is ICD-10 code Z28.31?
Z28.31 is the ICD-10-CM code for underimmunization for COVID-19 status, in the block Z20-Z29 (Persons with potential health hazards related to communicable diseases).
Is Z28.31 a billable code?
No. Z28.31 is a header code with more specific child codes; report one of the billable codes listed above.
What category does Z28.31 belong to?
It belongs to category Z28 – Immunization not carried out and underimmunization status.
Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.