2027 ICD-10-CM Diagnosis Code T88.1XXAOther complications following immunization, not elsewhere classified, initial encounter

ICD-10-CM Codes›S00–T88›T80-T88›T88

ICD-10-CM T88.1XXA
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

T88.1XXA is a billable ICD-10-CM diagnosis code for other complications following immunization, not elsewhere classified, 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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 865 through 866. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 1 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Complication of other surgical or medical care, injury, initial encounter.

Code Identity

ICD-10-CM Code
T88.1XXA
Billable Status
Yes — Valid for Submission
Code Describes
Other complications following immunization, not elsewhere classified, initial encounter
Short Description
Oth complications following immunization, NEC, init
Parent Code
T88.1
Other complications following immunization, not elsewhere classified

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT80-T88Complications of surgical and medical care, not elsewhere classified
CategoryT88Other complications of surgical and medical care, not elsewhere classified
This CodeT88.1XXAOther complications following immunization, not elsewhere classified, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Complication due to immunization
  • Complication due to vaccination
  • Complication of smallpox vaccination
  • Eczema vaccinatum
  • Feeling irritable
  • Fibrosarcoma
  • Generalized vaccinia
  • Inadvertent autoinoculation with Vaccinia virus following contact with smallpox vaccination site
  • Infection following immunization
  • Inflammatory neuropathy due to and following vaccination
  • Introduction procedure site rash
  • Introduction procedure site swelling
  • Irritability postvaccinal
  • Kaposi's varicelliform eruption caused by Vaccinia virus
  • Neurological complication following vaccination
  • Progressive vaccina
  • Scar of skin following first vaccination
  • Swelling of skin
  • Vaccination site cellulitis
  • Vaccination site lump
  • Vaccination site rash
  • Vaccination site swelling
  • Vaccination site vaccinia
  • Vaccine-induced fibrosarcoma
  • Vaccinia
  • Vaccinia keratitis

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 2027, published by CMS and the National Center for Health Statistics.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to T88.1XXA: its own notes plus those printed at T88.1, T88, block T80-T88, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From T88.1 Other complications following immunization, not elsewhere classified applies to 3 codes
  • vaccinia not from vaccine (B08.011)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From T88.1 Other complications following immunization, not elsewhere classified applies to 3 codes
  • anaphylactic shock due to serum (T80.5-)
  • other serum reactions (T80.6-)
  • postimmunization arthropathy (M02.2)
  • postimmunization encephalitis (G04.02)
  • postimmunization fever (R50.83)
From T88 Other complications of surgical and medical care, not elsewhere classified applies to 39 codes
  • complication following infusion, transfusion and therapeutic injection (T80.-)
  • complication following procedure NEC (T81.-)
  • complications of anesthesia in labor and delivery (O74.-)
  • complications of anesthesia in pregnancy (O29.-)
  • complications of anesthesia in puerperium (O89.-)
  • complications of devices, implants and grafts (T82-T85)
  • complications of obstetric surgery and procedure (O75.4)
  • dermatitis due to drugs and medicaments (L23.3, L24.4, L25.1, L27.0-L27.1)
  • poisoning and toxic effects of drugs and chemicals (T36-T65 with fifth or sixth character 1-4)
  • specified complications classified elsewhere
From Block T80-T88 Complications of surgical and medical care, not elsewhere classified applies to 1,683 codes
  • any encounters with medical care for postprocedural conditions in which no complications are present, such as:
  • artificial opening status (Z93.-)
  • closure of external stoma (Z43.-)
  • fitting and adjustment of external prosthetic device (Z44.-)
  • burns and corrosions from local applications and irradiation (T20-T32)
  • complications of surgical procedures during pregnancy, childbirth and the puerperium (O00-O9A)
  • mechanical complication of respirator [ventilator] (J95.850)
  • poisoning and toxic effects of drugs and chemicals (T36-T65 with fifth or sixth character 1-4 or 6)
  • postprocedural fever (R50.82)
  • specified complications classified elsewhere, such as:
  • cerebrospinal fluid leak from spinal puncture (G97.0)
  • colostomy malfunction (K94.0-)
  • disorders of fluid and electrolyte imbalance (E86-E87)
  • functional disturbances following cardiac surgery (I97.0-I97.1)
  • intraoperative and postprocedural complications of specified body systems (D78.-, E36.-, E89.-, G97.3-, G97.4, H59.3-, H59.-, H95.2-, H95.3, I97.4-, I97.5, J95.6-, J95.7, K91.6-, L76.-, M96.-, N99.-)
  • ostomy complications (J95.0-, K94.-, N99.5-)
  • postgastric surgery syndromes (K91.1)
  • postlaminectomy syndrome NEC (M96.1)
  • postmastectomy lymphedema syndrome (I97.2)
  • postsurgical blind-loop syndrome (K91.2)
  • ventilator associated pneumonia (J95.851)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Block T80-T88 Complications of surgical and medical care, not elsewhere classified applies to 1,683 codes
  • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)
  • code(s) to identify the specified condition resulting from the complication
  • code to identify devices involved and details of circumstances (Y62-Y82)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • code to identify any retained foreign body, if applicable (Z18.-)

Notes

General instructions on how these codes are used.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

7th Character

Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.

From T88 Other complications of surgical and medical care, not elsewhere classified applies to 39 codes
  • The appropriate 7th character is to be added to each code from category T88
Values for category T88 Encounter: Initial, Subsequent, Sequela
  • Ainitial encounter this code
  • Dsubsequent encounter
  • Ssequela

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name T88.1XXA, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming T88.1XXA: they are not reported together with it, unless the two conditions are unrelated.

  • B08.011 Vaccinia not from vaccine
    vaccinia (from vaccination) (generalized) (T88.1) names T88.1, which includes this code

Excludes2 1

These codes carry an Excludes2 note naming T88.1XXA: its condition is not part of those codes, and both may be reported when the patient has both.

  • T81 Complications of procedures, not elsewhere classified
    complications following immunization (T88.0-T88.1) names T88.0-T88.1, which includes this code

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INJ037
Complication of other surgical or medical care, injury, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Vaccinia

    the cutaneous and occasional systemic reactions associated with vaccination using smallpox (variola) vaccine.

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 T88.1XXA to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
999.0 Generalized vaccinia
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About T88.1XXAOverview

Is T88.1XXA a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other complications following immunization, not elsewhere classified, initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What does the 7th character A in T88.1XXA mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for other complications following immunization, not elsewhere classified, such as an emergency visit or first evaluation.

What MS-DRG does T88.1XXA group to?

When other complications following immunization, not elsewhere classified, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 866, 865, with relative weights from 0.8691 to 1.3153 depending on complications. Higher weights mean higher Medicare reimbursement.

Is T88.1XXA a CC or MCC?

CMS lists T88.1XXA as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 1 closely related codes in its exclusion list.

Can T88.1XXA be reported with B08.011?

Not as a rule. The Excludes1 note at T88.1, which applies to T88.1XXA, lists "vaccinia not from vaccine (B08.011)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).