Z28.39 Other underimmunization status

Billable ICD-10-CM code, FY2026. Exempt from present-on-admission (POA) reporting.

Applicable to

• Delinquent immunization status
• Lapsed immunization schedule status

Applies from Z28 Immunization not carried out and underimmunization status

Includes

• vaccination not carried out

Code also

• , if applicable, encounter for immunization safety counseling (Z71.85)

Applies from Z28.3 Underimmunization status

Use additional code

• 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-)

MS-DRG index

Defines the logic of DRG(s) 951 in MDC 23.

Medicare Code Edits (MCE v43.1 (April 2026))

• Unacceptable principal diagnosis: These codes describe a circumstance which influences care but is not a current illness or injury, or capture only an underlying condition, and are unacceptable as principal diagnosis.

Code annotations containing back-references to Z28.39

Back-references to Z28

• Code Also: Z71.85 Encounter for immunization safety counseling (", if applicable, immunization not carried out (Z28.-)")

Diagnosis Index entries for Z28.39

• Delinquent immunization status
• Lapsed immunization schedule status
• Status (post) › delinquent immunization
• Status (post) › lapsed immunization schedule
• Status (post) › underimmunization
• Underimmunization status

Nearby codes

• 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
• Z28.311 Partially vaccinated for COVID-19
• Z28.39 Other underimmunization status (this code)
• 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
• Z28.89 Immunization not carried out for other reason