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 Z28.310
Back-references to Z28
Code Also: Z71.85 Encounter for immunization safety counseling (", if applicable, immunization not carried out (Z28.-)")
Diagnosis Index entries for Z28.310
COVID-19 › unvaccinated (for)
Status (post) › underimmunization › COVID-19 › unvaccinated (for)
Underimmunization status › COVID-19 › unvaccinated (for)
Unimmunized › for COVID-19
Unvaccinated › for COVID-19
Nearby codes
Z28.20 Immunization not carried out because of patient decision for unspecified reason
Z28.21 Immunization not carried out because of patient refusal
Z28.29 Immunization not carried out because of patient decision for other reason