ICD-10 Code for Underimmunization Status
The ICD-10-CM code for underimmunization Status is Z28.39 — Other underimmunization status. This is the code the Alphabetic Index gives for underimmunization Status with no further qualifier, valid for FY2027 (October 1, 2026 – September 30, 2027).
Billable
Which underimmunization Status code should you use?
The Alphabetic Index lists 4 codes under Underimmunization status. Which one applies depends on the qualifier documented in the record — the type, site, cause, or associated condition. Find the qualifier below, then verify the code in the Tabular List before using it.
By type
| COVID-19 | Z28.31Not billable | Underimmunization for COVID-19 status |
Index terms and codes are reproduced from the official ICD-10-CM FY2027 release. The Alphabetic Index is a finding aid — a code must always be verified in the Tabular List before it is reported. Data sources