Summary & Overview
CPT 90635: H5N1 Cell-Culture Adjuvanted Influenza Vaccine
CPT code 90635 designates an H5N1 (avian influenza) vaccine produced from cell culture and formulated with an adjuvant, delivered via intramuscular injection. As a specialized influenza immunization targeting H5N1 strains, the code matters for national vaccination preparedness, public health immunization campaigns, and payer coverage policies for novel or pandemic influenza products. The designation clarifies billing for a distinct vaccine formulation that may be used in pandemic response or targeted prophylaxis.
Key payers covered in this publication include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of coverage considerations, common billing modifiers, and clinical context for administration. The report summarizes expected sites of service and describes the clinical role of adjuvanted, cell-culture influenza vaccines in enhancing immune response compared with traditional egg-based products.
This publication offers practical benchmarks for coding and billing workflows, a summary of payer coverage patterns where available, and policy-relevant notes on how this vaccine is categorized for outpatient immunization services. Data not available in the input is noted where applicable.
Billing Code Overview
CPT code 90635 represents an H5N1 influenza (bird flu) vaccine that is cell-culture derived and formulated with an adjuvant to enhance the immune response. The product is administered as an intramuscular injection.
Service type: Vaccination / Immunization injection
Typical site of service: Outpatient clinic, physician office, public health clinic, or pharmacy immunization setting
Clinical & Coding Specifications
Clinical Context
A 42-year-old adult with occupational exposure to poultry presents to an outpatient clinic during a targeted H5N1 vaccination campaign. The patient is medically stable, consents to vaccination, and has no contraindications such as severe allergic reaction to prior H5N1 vaccine components. The clinic verifies identity and insurance, reviews immunization history, screens for acute illness and allergies, documents informed consent, and performs a brief medication/allergy review. The vaccine product, an H5N1 cell culture–derived, adjuvanted intramuscular formulation coded as 90635, is prepared per manufacturer instructions. The vaccine is administered intramuscularly, typically in the deltoid muscle, using standard aseptic technique. Post-vaccination observation for 15–30 minutes occurs to monitor for immediate adverse reactions. The encounter documentation includes vaccine lot number, expiration date, administration site, route, dose, informed consent, and any observed immediate reactions. Billing uses 90635 for the vaccine; applicable modifiers such as 52 (reduced services) or 53 (discontinued procedure) are appended when clinically appropriate. Typical sites of service are outpatient primary care clinics, occupational health clinics, public health clinics, and designated vaccination centers. This workflow applies to adult immunization visits, occupational risk mitigation programs, and targeted public health vaccination efforts during an H5N1 outbreak or preparedness campaign.
Coding Specifications
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