Z28.31
Underimmunization for COVID-19 status
Non-billable headerNot valid on its own. Use one of the more specific codes under it.
Z28.31 is a non-billable ICD-10-CM code header for underimmunization for COVID-19 status. Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. The more specific codes under it are Z28.310 Unvaccinated for COVID-19 and Z28.311 Partially vaccinated for COVID-19. Its coding notes include a Use additional code instruction and a Code also instruction.
Use additional code
Add the listed code as a secondary code, if known.
Inherited from 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-)
Code also
Two codes may be needed to describe the condition. This note gives no sequencing order.
Includes
Further defines or gives examples of the content of the category.
Inherited from Z28 Immunization not carried out and underimmunization status
- vaccination not carried out
Notes
This code
- These codes should not be used for individuals who are not eligible for the COVID-19 vaccines, as determined by the healthcare provider.
Also from chapter/block level (3 notes)
Inherited from Chapter 21 Factors influencing health status and contact with health services
- Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
- (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
- (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 4 entries