2026 ICD-10-CM Diagnosis Code T88.0XXAInfection following immunization, initial encounter
T88.0XXA is a billable ICD-10-CM diagnosis code for infection following immunization, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 856 through 858, 867 through 869. Coders also document this condition as COVID-19. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Complication of other surgical or medical care, injury, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- COVID-19
- Infection following immunization
- Primary immunodeficiency with post-measles-mumps-rubella vaccine viral infection
- SARS-CoV-2 breakthrough infection
- Sepsis following infusion, injection, transfusion AND/OR vaccination
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Other complications of surgical and medical care, not elsewhere classified (T88). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Vaccines
Vaccines are injections (shots), liquids, pills, or nasal sprays that you take to teach your body's immune system to recognize and defend against harmful germs. For example, there are vaccines to protect against diseases caused by:
The full article covers:
- What are vaccines?
- What are the types of vaccines?
- What happens in an immune response?
- What are immunization and vaccination?
- Why are vaccines important?
- What is community immunity?
- Are vaccines safe?
- What is a vaccine schedule?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T88.0XXA to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T88.0XXAOverview
Is T88.0XXA (Infection following immunization) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report infection following immunization, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T88.0XXA mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for infection following immunization, such as an emergency visit or first evaluation.
What MS-DRG does T88.0XXA group to?
When infection following immunization, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 856, 857, 858, 867, 868, 869, with relative weights from 0.7297 to 4.5487 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of T88.0XXA?
Under the General Equivalence Mappings, infection following immunization, initial encounter converts to ICD-9-CM 999.39 (infect fol infus/inj/vac). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
