| Z28 | Immunization not carried out and underimmunization status | NON-BILLABLE CODE |
| Z28.0 | Immunization not carried out because of contraindication | NON-BILLABLE CODE |
| Z28.01 | Immunization not carried out because of acute illness of patient | BILLABLE CODE |
| Z28.02 | Immunization not carried out because of chronic illness or condition of patient | BILLABLE CODE |
| Z28.03 | Immunization not carried out because of immune compromised state of patient | BILLABLE CODE |
| Z28.04 | Immunization not carried out because of patient allergy to vaccine or component | BILLABLE CODE |
| Z28.09 | Immunization not carried out because of other contraindication | BILLABLE CODE |
| Z28.1 | Immunization not carried out because of patient decision for reasons of belief or group pressure | BILLABLE CODE |
| Z28.2 | Immunization not carried out because of patient decision for other and unspecified reason | NON-BILLABLE CODE |
| Z28.20 | Immunization not carried out because of patient decision for unspecified reason | BILLABLE CODE |
| Z28.21 | Immunization not carried out because of patient refusal | BILLABLE CODE |
| Z28.29 | Immunization not carried out because of patient decision for other reason | BILLABLE CODE |
| Z28.3 | Underimmunization status | NON-BILLABLE CODE |
| Z28.31 | Underimmunization for COVID-19 status | NON-BILLABLE CODE |
| Z28.310 | Unvaccinated for COVID-19 | BILLABLE CODE |
| Z28.311 | Partially vaccinated for COVID-19 | BILLABLE CODE |
| Z28.39 | Other underimmunization status | BILLABLE CODE |
| Z28.8 | Immunization not carried out for other reason | NON-BILLABLE CODE |
| Z28.81 | Immunization not carried out due to patient having had the disease | BILLABLE CODE |
| Z28.83 | Immunization not carried out due to unavailability of vaccine | BILLABLE CODE |
| Z28.89 | Immunization not carried out for other reason | BILLABLE CODE |
| Z28.9 | Immunization not carried out for unspecified reason | BILLABLE CODE |
