2026 ICD-10-CM Diagnosis Code T50.B95AAdverse effect of other viral vaccines, initial encounter

ICD-10-CM Codes›S00–T88›T36-T50›T50

ICD-10-CM T50.B95A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T50.B95A is a billable ICD-10-CM diagnosis code for adverse effect of other viral vaccines, 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 917 through 918. The code is not accepted as a principal diagnosis by the Medicare Code Editor. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Adverse effects of drugs and medicaments, initial encounter.

Code Identity

ICD-10-CM Code
T50.B95A
Billable Status
Yes — Valid for Submission
Code Describes
Adverse effect of other viral vaccines, initial encounter
Short Description
Adverse effect of other viral vaccines, initial encounter
Same as the full description in the CMS dataset.
Parent Code
T50.B95
Adverse effect of other viral vaccines

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT36-T50Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances
CategoryT50Poisoning by, adverse effect of and underdosing of diuretics and other and unspecified drugs, medicaments and biological substances
This CodeT50.B95AAdverse effect of other viral vaccines, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T50.B95A.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adverse reaction to component of vaccine product containing Japanese encephalitis virus antigen
  • Adverse reaction to component of vaccine product containing only Human alphaherpesvirus 3 recombinant surface glycoprotein E antigen
  • Adverse reaction to component of vaccine product containing only live attenuated Human alphaherpesvirus 3 antigen
  • Adverse reaction to component of Vaccine product containing Rotavirus antigen
  • Adverse reaction to COVID-19 antigen vaccine
  • Adverse reaction to COVID-19 DNA plasmid encoding spike protein vaccine
  • Adverse reaction to COVID-19 mRNA vaccine
  • Adverse reaction to COVID-19 non-replicating viral vector vaccine
  • Adverse reaction to COVID-19 recombinant spike protein antigen vaccine
  • Adverse reaction to COVID-19 vaccine
  • Adverse reaction to COVID-19 virus-like particle antigen vaccine
  • Adverse reaction to diphtheria and acellular pertussis and Haemophilus influenzae type b and hepatitis B and inactivated poliomyelitis and tetanus vaccine
  • Adverse reaction to Haemophilus influenzae type b vaccine
  • Adverse reaction to hepatitis A vaccine
  • Adverse reaction to hepatitis B vaccine
  • Adverse reaction to Human papillomavirus vaccine
  • Adverse reaction to inactivated whole COVID-19 antigen vaccine
  • Adverse reaction to influenza virus vaccine
  • Adverse reaction to measles and mumps and rubella vaccine
  • Adverse reaction to measles vaccine
  • Adverse reaction to mumps vaccine
  • Adverse reaction to pertussis vaccine
  • Adverse reaction to poliomyelitis vaccine
  • Adverse reaction to rabies vaccine
  • Adverse reaction to rubella vaccine
  • Adverse reaction to Tick-borne encephalitis vaccine
  • Adverse reaction to Varicella-zoster virus vaccine
  • Adverse reaction to viral vaccine
  • Adverse reaction to yellow fever vaccine
  • Anaphylaxis caused by component of vaccine product against severe acute respiratory syndrome coronavirus 2
  • Anaphylaxis caused by rotavirus vaccine
  • Anaphylaxis caused by vaccine containing Human alphaherpesvirus 3 antigen
  • Anaphylaxis caused by vaccine product containing Hepatitis A virus antigen
  • Anaphylaxis caused by vaccine product containing Hepatitis B virus antigen
  • Anaphylaxis caused by vaccine product containing human alphaherpesvirus 3 recombinant surface glycoprotein E antigen
  • Anaphylaxis caused by vaccine product containing Human papillomavirus antigen
  • Anaphylaxis caused by vaccine product containing human poliovirus antigen
  • Anaphylaxis caused by vaccine product containing Influenza virus antigen
  • Anaphylaxis caused by vaccine product containing live attenuated human alphaherpesvirus 3 antigen
  • Anaphylaxis caused by vaccine product containing Measles morbillivirus and Mumps orthorubulavirus and Rubella virus antigens
  • Anaphylaxis caused by vaccine product containing only Haemophilus influenzae type b antigen
  • Encephalitis caused by hepatitis A vaccine
  • Encephalitis caused by hepatitis B vaccine
  • Encephalitis caused by influenza vaccine
  • Encephalitis caused by measles vaccine
  • Encephalitis caused by mumps vaccine
  • Encephalitis caused by polio vaccine
  • Encephalitis caused by rabies vaccine
  • Encephalitis caused by rubella vaccine
  • Encephalitis caused by yellow fever vaccine
  • Thrombosis with thrombocytopenia syndrome following vaccination
  • TTS following non-replicating adenovirus vector COVID-19 vaccination

Coding GuidelinesGuidance

When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug.

The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of diuretics and other and unspecified drugs, medicaments and biological substances (T50). 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.

CCSR INJ028
Adverse effects of drugs and medicaments, initial encounter
Default principal diagnosis: inpatient No · outpatient Yes

Clinical InformationClinical

  • Rubella Vaccine

    a live attenuated virus vaccine of duck embryo or human diploid cell tissue culture origin, used for routine immunization of children and for immunization of nonpregnant adolescent and adult females of childbearing age who are unimmunized and do not have serum antibodies to rubella. children are usually immunized with measles-mumps-rubella combination vaccine. (dorland, 28th ed)

Table of Drugs and ChemicalsClinical

Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.

SubstanceAccidentalSelf-harmAssaultUndeter­minedAdverse
Effect		Under­dosing
DiplovaxT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
Influenza vaccineT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
Measles virus vaccine (attenuated)T50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
MeruvaxT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
MumpsvaxT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
OrimuneT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
Poliomyelitis vaccineT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
Rubella vaccineT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
Rubeola vaccineT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
SynagisT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
Viral vaccine NECT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
YellowT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
Yellow::fever vaccineT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
Yellow::jasmineT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96
Yellow::phenolphthaleinT50.B91T50.B92T50.B93T50.B94T50.B95T50.B96

Patient EducationClinical

Vaccine Safety

Vaccines play an important role in keeping us healthy. They protect us from serious and sometimes deadly diseases. 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. The germs could be viruses or bacteria.

The full article covers:

  • What are vaccines?
  • Do vaccines cause side effects?
  • How are vaccines tested for safety?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert T50.B95A to ICD-9-CMHistory

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

ICD-9-CM
995.29 Adv eff med/biol NEC/NOS
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
E949.6 Adv eff viral vacc NEC
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About T50.B95AOverview

Is T50.B95A (Adverse effect of other viral vaccines) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report adverse effect of other viral vaccines, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T50.B95A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for adverse effect of other viral vaccines, such as an emergency visit or first evaluation.

What MS-DRG does T50.B95A group to?

On inpatient claims, adverse effect of other viral vaccines, initial encounter maps to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.

Can T50.B95A be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because adverse effect of other viral vaccines, initial encounter describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

What is the ICD-9 equivalent of T50.B95A?

Under the General Equivalence Mappings, adverse effect of other viral vaccines, initial encounter converts to ICD-9-CM 995.29 (adv eff med/biol NEC/NOS) and E949.6 (adv eff viral vacc NEC). 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.