Summary & Overview
HCPCS G2156: Td/Tdap Vaccination Status or Contraindication
HCPCS Level II code G2156 flags patients who lack documentation of at least one Td or Tdap vaccine within the nine years before a measurement period or who have a recorded contraindication to Td/Tdap. Nationally, this code is important for tracking immunization gaps and documenting clinical exceptions to vaccination in preventive care quality measures. Use of this code can affect immunization reporting, quality metrics, and care management workflows across outpatient settings.
Key payers covered in this overview include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of what the code represents, the typical service setting, and the types of clinical documentation it captures. The publication also outlines what stakeholders can expect to learn about reporting and measurement implications: how the code is used to document vaccine omission or contraindication, how it relates to preventive care quality measures, and where data may be limited. This summary does not include state-specific guidance and is written for a national audience. Data not available in the input for associated taxonomies, ICD-10 diagnoses, related codes, and detailed payer-specific billing guidance.
Billing Code Overview
HCPCS Level II code G2156 indicates that a patient did not receive at least one tetanus-diphtheria (Td) vaccine or one tetanus-diphtheria-acellular pertussis (Tdap) vaccine within the nine years prior to the start of the measurement period through the end of the measurement period, or has a documented history of a contraindication to Td or Tdap vaccination. Contraindications include anaphylaxis to a Td or Tdap vaccine or its components, or encephalopathy following Td or Tdap vaccination (post-tetanus, post-diphtheria, or post-pertussis vaccination encephalitis).
Service Type: Preventive measurement / immunization status assessment — the code documents vaccination history or contraindication status relevant to preventive care quality measurement.
Typical Site of Service: Outpatient clinical settings such as primary care offices, pediatric clinics, family medicine practices, and other ambulatory care locations where vaccination history and contraindications are assessed.
Clinical & Coding Specifications
Clinical Context
A 28-year-old adult presents to a primary care clinic for routine preventive care and vaccine review during the measurement period. The patient’s immunization history reveals no documented tetanus-diphtheria (Td) or tetanus-diphtheria-acellular pertussis (Tdap) vaccine administered within nine years prior to the start of the measurement period through the end of the measurement period. The clinic nurse reviews the record for contraindications and documents a reported history of anaphylaxis to a prior Tdap vaccine several years earlier. Per immunization surveillance and quality-measure reporting, the patient is eligible for a contraindication-based exclusion rather than vaccine administration. The clinical workflow includes verification of immunization records, review of adverse reaction history, documentation of the contraindication in the medical record and immunization registry, billing using the HCPCS Level II code G2156 to indicate the patient did not receive at least one Td or Tdap vaccine in the specified lookback period or has a qualifying contraindication, and communication of the exclusion in quality reporting to payors and registries.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
22 | Increased procedural services | Use when additional documentation supports increased complexity of consultation or documentation required to determine and document contraindications and vaccine history. |