The correct CPT code for a flu shot depends on two components: the influenza vaccine product code and the administration code. Accurate selection is required for Medicare, Medicaid, and commercial payer reimbursement in the United States.
What Is a CPT Code?
Current Procedural Terminology (CPT) codes are standardized numeric codes maintained by the American Medical Association used to describe medical procedures and services for billing and reporting.
Influenza vaccination requires:
- One CPT code for the vaccine product
- One CPT code for administration
Failure to bill both correctly results in underpayment or denial.
CPT Code for a Flu Shot: Core Codes
Influenza Vaccine Product CPT Codes
Commonly used influenza vaccine CPT codes include:
- 90630 – Influenza virus vaccine, quadrivalent, preservative-free, IM
- 90653 – Influenza vaccine, trivalent, adjuvanted, ≥65 years
- 90654 – Influenza vaccine, quadrivalent, split virus, IM
- 90656 – Influenza vaccine, trivalent, split virus, IM
- 90657 – Influenza vaccine, split virus, IM, pediatric dose
- 90658 – Influenza vaccine, trivalent, split virus, IM
- 90662 – Influenza vaccine, high-dose, ≥65 years
- 90672 – Influenza vaccine, live, intranasal
- 90674 – Influenza vaccine, quadrivalent, cell culture-based
- 90682 – Influenza vaccine, recombinant, preservative-free
- 90685 / 90686 / 90687 / 90688 – Quadrivalent influenza vaccines by age group and dosage
Exact code selection depends on:
- Patient age
- Vaccine formulation
- Dose volume
- Route of administration
CPT Codes for Flu Shot Administration
Administration Codes
- 90471 – Immunization administration (one vaccine)
- 90472 – Each additional vaccine (same encounter)
Medicare-Specific Administration Code
- G0008 – Administration of influenza virus vaccine (Medicare only)
For Medicare patients, G0008 replaces 90471.
CPT Code for Flu Shot in Medicare Billing
Medicare billing requires:
- One influenza vaccine CPT code
- G0008 for administration
- No patient copay or deductible (preventive benefit)
Incorrect use of 90471 instead of G0008 causes claim rejection under Medicare Part B.
CPT Code for Flu Shot in Children
Pediatric billing considerations:
- Age-specific vaccine codes (e.g., 90685 vs 90686)
- Two-dose schedule for first-time recipients under age 9
- Administration billed per encounter, not per dose unless separate visits
ICD-10 Diagnosis Code for Flu Shot
Common diagnosis codes used with flu shot CPT codes:
- Z23 – Encounter for immunization
Z23 is required for claim acceptance across most payers.
Modifiers and Place of Service
Common Modifiers
- Modifier 25 – When flu shot is given with a separately identifiable E/M visit
- Modifier SL – State-supplied vaccine (Medicaid programs)
Place of Service Codes
- 11 – Office
- 19 / 22 – Outpatient hospital
- 60 – Mass immunization center
- 01 – Pharmacy
Common Billing Errors
- Billing vaccine without administration code
- Using adult vaccine CPT code for pediatric patient
- Incorrect Medicare administration code
- Missing ICD-10 Z23
- Using expired CPT codes from prior flu seasons
Unique Clinical Takeaways
1. Age-Specific Vaccine Coding Directly Impacts Safety and Reimbursement
High-dose and adjuvanted influenza vaccines are clinically recommended for adults aged 65 and older due to reduced immune response with aging. Using standard-dose CPT codes for this population can lead to both clinical underprotection and payer audits. Accurate age-matched coding aligns clinical efficacy with compliance.
2. Patient Experience and Access Settings Affect CPT Selection
Flu shots administered in pharmacies, mass immunization clinics, or workplace settings require precise place-of-service and administration coding. Misalignment between clinical setting and CPT structure is a leading cause of delayed reimbursement in preventive care claims.
3. Differential Diagnosis and Preventive Coding Separation
Influenza vaccination encounters must be clearly separated from visits addressing acute respiratory symptoms. When patients present with fever or viral symptoms, clinicians must document deferral of vaccination or clearly distinguish preventive services to avoid medical necessity denials and compliance risk.
CPT Code Updates and Annual Changes
Influenza vaccine CPT codes are updated annually to reflect:
- New vaccine formulations
- Discontinued products
- Revised age indications
Billing teams must verify codes at the start of each flu season.
Flu Shot CPT Codes vs HCPCS Codes
- CPT codes identify the vaccine product
- HCPCS Level II codes (e.g., G0008) are used primarily by Medicare
- Both may appear on the same claim depending on payer
Compliance and Audit Considerations
Influenza vaccination is a high-volume preventive service and a frequent audit target. Documentation must include:
- Vaccine name and lot number
- Route and site
- Patient age
- Informed consent
- Vaccine Information Statement (VIS) date
Frequently Asked Questions
Is there one universal CPT code for a flu shot?
No. Each influenza vaccine formulation has a unique CPT code.
Can you bill only the administration code?
Only if the vaccine is supplied at no cost by a state or federal program and modifier SL is used when required.
Does Medicare pay for flu shots every year?
Yes. Medicare covers one influenza vaccine per season.