ICD-10-CM 2027
ICD-10 code for Postvaccinal encephalitis
Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis
From the official ICD-10-CM alphabetic index entry “Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute) › postvaccinal”. Page updated September 29, 2026.
About coding Postvaccinal encephalitis
The ICD-10-CM code for Postvaccinal encephalitis is G04.02 (Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis).
Within G04.0 (acute disseminated encephalitis and encephalomyelitis (ADEM)), G04.02 is specifically for Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis. Related codes cover acute disseminated encephalitis and encephalomyelitis, unspecified (G04.00) and postinfectious acute disseminated encephalitis and encephalomyelitis (postinfectious ADEM) (G04.01).
Use an additional code to identify the vaccine (T50.A-, T50.B-, T50.Z-).
As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.
Common questions about Postvaccinal encephalitis ICD-10 codes
What is the ICD-10 code for Postvaccinal encephalitis?
- G04.02 — Postimmunization acute disseminated encephalitis, myelitis and encephalomyelitis.
Is G04.02 billable?
- Yes. G04.02 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can G04.02 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict G04.02 as a principal diagnosis.
Is G04.02 a CC or MCC?
- G04.02 is an MCC (major complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.