M1161 Anaphylaxis (HCPCS) Reimbursement & Policy | OpenPayer

Summary & Overview

HCPCS M1161: Anaphylaxis Due to Tetanus/Diphtheria/Pertussis Vaccine, Pediatric

HCPCS Level II code M1161 documents a history of anaphylaxis due to the tetanus, diphtheria, or pertussis vaccine occurring on or before a patient’s 13th birthday. This code signals a clinically significant vaccine-related severe allergic reaction and is used to flag patients with prior anaphylaxis when considering future immunizations or documenting adverse event history. Nationally, clear capture of vaccine-related anaphylaxis supports patient safety, continuity of care, and appropriate clinical decision-making across immunization programs.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of the clinical context for M1161, typical sites of service, and the service type. The publication outlines common billing considerations tied to documentation of vaccine-related anaphylaxis and highlights which administrative elements are available or absent in the source input. Benchmarks, payer policy nuances, and related coding guidance are summarized where present; missing inputs are noted as unavailable.

This summary is written for a national audience and is intended to help clinicians, billing staff, and policy analysts understand the purpose of M1161, where it is commonly applied, and what information is included in the source data.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareM1161HCPCS Level IIvaccine adverse eventanaphylaxisimmunization complicationpediatric vaccineoutpatient careemergency department

Billing Code Overview

HCPCS Level II code M1161 documents a history of anaphylaxis attributed to the tetanus, diphtheria, or pertussis vaccine occurring any time on or before the patient's 13th birthday. The code captures a vaccine-related severe allergic reaction as part of the patient’s medical record.

Service type: Vaccine-related adverse event documentation / Immunization complication diagnosis

Typical site of service: Outpatient clinics, emergency departments, urgent care centers, and immunization or public health clinics

Data not available in the input.

Clinical & Coding Specifications

Clinical Context

A 10-year-old child presents to the pediatric clinic with a documented history of severe immediate hypersensitivity (anaphylaxis) that occurred after administration of a tetanus, diphtheria, or pertussis-containing vaccine on or before their 13th birthday. The caregiver brings prior immunization records and an emergency department note confirming anaphylaxis (respiratory distress, hypotension, or angioedema requiring epinephrine). The clinical workflow includes confirmation of the diagnosis, review of vaccine component exposure, allergy/immunology consultation as indicated, documentation of vaccine contraindication in the permanent medical record and Immunization Information System, discussion of alternative vaccine options or deferral, provision of anaphylaxis action plan and medical alert guidance, and communication of contraindication to primary care and school health services. Billing for the patient’s vaccine contraindication is linked to the HCPCS Level II code M1161, used to indicate anaphylaxis to tetanus-, diphtheria-, or pertussis-containing vaccines occurring on or before age 13. Typical sites of service include outpatient pediatric clinics, primary care offices, allergy/immunology clinics, and emergency departments for initial event documentation. The typical patient scenario involves documentation review, clinical evaluation, counseling, and care coordination rather than administration of an immunization at that encounter.

Coding Specifications

For M1161, the most clinically relevant modifiers are listed below with typical use.

Modifier	Description	When to Use

HCPCS Level II M1362: Patients Who Died During the Measurement Period

HCPCS-M1340-WHODAS-SDS-INDEX-ASSESSMENT

HCPCS M1340: 12-item WHODAS 2.0 or SDS Index Assessment

HCPCS-M1413-PD-L1-POSITIVE-PRE-FIRST-LINE-IMMUNOTHERAPY

HCPCS M1413: PD-L1 Positive Prior to First-Line Immune Checkpoint Inhibitor Therapy

HCPCS-M1201-MEDICAL-REASON-NO-ACEI-OR-ARB

HCPCS M1201: Documentation of Medical Reason for Not Prescribing ACE-i/ARB Therapy

HCPCS-M1346-PAM-NO-NET-INCREASE-4-12-MONTHS

HCPCS Level II M1346: No Net PAM Score Increase (4–12 Months)

HCPCS-M1266-SNF-ADMISSION

HCPCS M1266: Skilled Nursing Facility Admission

HCPCS-M1267-KIDNEY-TRANSPLANT-WAITLIST-INACTIVE-STATUS

HCPCS Level II M1267: Kidney/Kidney-Pancreas Transplant Waitlist Inactive Status

HCPCS-M1461-CHRONIC-HEPATITIS-C-DIAGNOSIS

HCPCS M1461: Chronic Hepatitis C Diagnosis

HCPCS-M1415-NO-POSITIVE-PD-L1-BEFORE-FIRST-LINE-IMMUNOTHERAPY

HCPCS Level II M1415: No Positive PD-L1 Before First-Line Immunotherapy

HCPCS-M1317-COUNSELING-CSP-CONNECTION-OPT-OUT

HCPCS M1317: Counseling on Community Service Provider Connection, Patient Opt-Out

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Taxonomy Code	Specialty	Notes
`207Q00000X`	Pediatric Medicine	Primary specialty evaluating childhood vaccine reactions and contraindications.
`207K00000X`	Allergy & Immunology	Specialty for diagnostic evaluation and management of vaccine anaphylaxis and testing.
`207L00000X`	Emergency Medicine	Initial evaluation and stabilization of anaphylaxis in acute events.
`207P00000X`	Family Medicine	Primary care follow-up, documentation, and immunization planning.
`208000000X`	General Practice	Community-based documentation and care coordination for vaccine contraindications.

ICD-10 Code	Description	Clinical Relevance
Data not available in the input.	Data not available in the input.	Data not available in the input.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`99213`	Office or other outpatient visit for the evaluation and management of an established patient, typically 15 minutes	Common outpatient visit level used for evaluation, documentation, and counseling regarding vaccine anaphylaxis and contraindication certification.
`99214`	Office or other outpatient visit for the evaluation and management of an established patient, typically 25 minutes	Used when evaluation and counseling are more complex or time-consuming due to detailed history review, coordination with specialists, or multiple comorbidities.
`99406`	Smoking and tobacco use cessation counseling, intermediate, greater than 3 minutes up to 10 minutes	Data not directly related; include only if relevant counseling is provided (otherwise not typically used).
`94760`	Noninvasive ear or eye allergy testing — skin prick testing (Note: actual CPT for skin testing varies)	Allergy testing and evaluation may be performed by allergy specialists to assess sensitivities related to vaccine components; use specialty-appropriate testing codes.
`95165`	Professional services for the supervision of allergy immunotherapy not including provisions of allergenic extracts	Used in allergy clinic settings when immunotherapy is considered unrelated to vaccine contraindication but part of allergy care coordination.

`22`	Increased Procedural Services	Use when work required for documentation, counseling, or coordination associated with contraindication substantially exceeds typical services (rare).
`23`	Unusual Anesthesia	Not typically applicable; include only if unrelated anesthesia was provided for an associated procedure.
`52`	Reduced Services	Use if an expected component of the visit was not completed (e.g., partial evaluation).
`53`	Discontinued Procedure	Use if evaluation was begun but terminated due to patient instability.
`54`	Surgical Care Only	Not commonly applicable; use if another provider bills the postoperative care only.
`55`	Postoperative Management Only	Not commonly applicable; use when only postoperative visits are billed by this provider.
`56`	Preoperative Management Only	Use when documenting only pre-procedure evaluation prior to a separate definitive service.
`62`	Two Surgeons	Rarely applicable; use only if two qualified providers shared in a surgical procedure related to care.
`AS`	Accredited Surgical Assistant	Not typically applicable; include only if an accredited assistant provided services during a related surgical encounter.
`CO`	Left or Right Modifier (place of service)	Use to indicate laterality for services where laterality is reportable (uncommon for `M1161`).
`CQ`	Service Delivered Under an Alternate Payment Model (APM)	Use when this encounter is billed under a qualified APM arrangement.
`QK`	Medical Direction of Two, Three, or Four Assistants	Use if reporting supervision/medical direction consistent with CMS rules for assistants.
`QX`	CRNA Service with Medical Direction	Use if a certified registered nurse anesthetist provided care under direction (rare for this code).
`QY`	Medical Direction of One CRNA by a Physician	Use when applicable under anesthesia contexts (rare for `M1161`).

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