Z28.9 Immunization not carried out for unspecified reason

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

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)

MS-DRG index

Defines the logic of DRG(s) 795 in MDC 15.

Approximate ICD-9-CM (GEMs)

• V64.00 Vaccination not carried out, unspecified reason

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 Z28.9

Back-references to Z28

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

Diagnosis Index entries for Z28.9

• Delay, delayed › vaccination
• Immunization › not done (not carried out)
• Vaccination (prophylactic) › delayed

Nearby codes

• 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
• Z28.9 Immunization not carried out for unspecified reason (this code)