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)
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-)
Applies from Z28.31 Underimmunization for COVID-19 status
Notes
These codes should not be used for individuals who are not eligible for the COVID-19 vaccines, as determined by the healthcare provider.
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 Z28.311
Back-references to Z28
Code Also: Z71.85 Encounter for immunization safety counseling (", if applicable, immunization not carried out (Z28.-)")
Diagnosis Index entries for Z28.311
COVID-19 › partially vaccinated (for)
Immunization › partial › for COVID-19
Status (post) › underimmunization › COVID-19 › partially vaccinated (for)
Underimmunization status › COVID-19 › partially vaccinated (for)
Vaccination (prophylactic) › partial › for COVID-19
Nearby codes
Z28.21 Immunization not carried out because of patient refusal
Z28.29 Immunization not carried out because of patient decision for other reason