CPT 90638: Quadrivalent mRNA Influenza Vaccine, 60 mcg/0.5 mL

CPT code 90638 represents a quadrivalent, mRNA-based influenza vaccine delivered by intramuscular injection at a dose of 60 mcg/0.5 mL. As an mRNA formulation for seasonal influenza prevention, this code is relevant to broad immunization programs across outpatient clinical settings, pharmacies, and public health initiatives. Widespread use of mRNA influenza vaccines can influence vaccine administration patterns, billing workflows, and payer coverage policies nationwide.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The summary outlines how these payers typically approach coverage for seasonal influenza vaccines and identifies common billing considerations clinicians may encounter when submitting claims for immunizations.

Readers will gain a concise clinical and billing orientation to 90638, including expected service types and sites of care, typical payer coverage landscape, common modifiers referenced in clinical practice, and where to find related policy updates. The publication also provides benchmarks and practical coding context to support accurate claim submission and alignment with payer documentation requirements. Data not available in the input is noted where applicable.

Billing Code Overview

CPT code 90638 describes a quadrivalent, mRNA-based influenza vaccine administered by intramuscular injection. The vaccine dose is 60 mcg/0.5 mL and the code indicates a preventive immunization intended to reduce the patient’s risk of contracting influenza.

Service Type: Vaccine administration (intramuscular immunization)

Typical Site of Service: Outpatient settings such as physician offices, clinics, pharmacies, and other ambulatory care locations where intramuscular vaccines are delivered.

Clinical Context

A 68-year-old patient presents to an outpatient primary care clinic during influenza season for routine immunization. The patient has chronic obstructive pulmonary disease and diabetes mellitus and requests the annual influenza vaccine. After verification of immunization history and assessment for contraindications (egg allergy, prior severe vaccine reaction, current moderate or severe illness), the clinician administers a single intramuscular dose of a quadrivalent mRNA-based influenza vaccine, 90638 (60 mcg/0.5 mL) in the deltoid. The clinic documents vaccine lot number, manufacturer, administration site, route, dose, informed consent, and any immediate adverse reaction observation. Typical billing includes the vaccine code 90638 and may include an administration code when required by the payer. The usual site of service is an outpatient clinic, primary care office, or community vaccination clinic. Common clinical workflow steps include pre-visit screening, vaccine review and consent, preparation and intramuscular injection, post-vaccination observation for 15 minutes (longer if history of allergic reaction), and documentation in the electronic health record and state immunization registry.

Coding Specifications

Modifier	Description	When to Use
`22`	Increased procedural services	Use when the vaccine administration or related clinical work requires substantially greater effort or resources than typical and documentation supports increased complexity.

Taxonomy Code	Specialty	Notes
207Q00000X	Family Medicine	Primary care providers commonly administer influenza vaccines in outpatient settings.
207RG0300X	Internal Medicine	Internists provide adult immunizations including `90638`.
363LF0000X	Nurse Practitioner	NPs frequently administer vaccines in clinics and community settings.
364S00000X	Physician Assistant	PAs commonly perform vaccine assessment and administration.
261QM0800X	Public Health Immunization Specialist	Public health nurses and immunization program staff administer influenza vaccines in clinics and mass vaccination events.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`Z23`	Encounter for immunization	Primary diagnosis code used to report administration of `90638` for routine influenza immunization.
`J44.9`	Chronic obstructive pulmonary disease, unspecified	Chronic pulmonary disease is an indication for priority influenza vaccination due to increased risk of complications.
`E11.9`	Type 2 diabetes mellitus without complications	Diabetes is a comorbidity that increases influenza risk and supports vaccine administration.
`Z00.00`	Encounter for general adult medical examination without abnormal findings	Preventive visit during which influenza vaccine `90638` may be administered.
`Z91.018`	Patient has a history of adverse reaction to another vaccine	Documented history of prior vaccine reaction may affect vaccine choice or observation period; relevant to planning administration.
`Z57.0`	Occupational exposure to radiation	Example of a social/occupational code that may appear in the chart; not a contraindication but can coexist with immunization encounter.
`Z86.19`	Personal history of other infectious and parasitic diseases	May be present in medical history and relevant to immunization planning and risk assessment.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`90460`	Immunization administration through 18 years of age via any route, with counseling by physician or other qualified health care professional; first vaccine/toxoid component	Used for pediatric immunization counseling/administration when multiple vaccines are given; not typically used for adult `90638` but relevant if pediatric patient and multiple components are administered.
`90471`	Immunization administration (single vaccine/toxoid) intramuscular or subcutaneous	Common administration code paired with vaccine codes like `90638` when payer requires a separate administration code for a single vaccine in adults.
`90472`	Immunization administration, each additional vaccine/toxoid (when multiple vaccines are administered)	Used if `90638` is given with other vaccines during same encounter.
`G0008`	Administration of influenza virus vaccine	Medicare-specific HCPCS for influenza vaccine administration in adults when applicable; may be used in billing workflows for administration separate from the vaccine product code.
`90756`	Influenza vaccine, live, intranasal, quadrivalent	Alternative influenza vaccine option; listed to delineate other influenza vaccine products that may be chosen instead of `90638` based on clinical considerations.
`90473`	Immunization administration by intranasal or oral route; first vaccine/toxoid component	Included to show alternate administration routes when different vaccine formulations are used in the same clinical setting.

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Summary & Overview