Is it recommended to administer the influenza vaccine in the buttocks?

Influenza Vaccine Administration Site: Avoid the Buttocks

The influenza vaccine should not be administered in the buttocks as this site is not recommended by the Advisory Committee on Immunization Practices (ACIP). 1

Proper Administration Sites for Influenza Vaccines

For Adults and Older Children:

• Recommended site: Deltoid muscle 1, 2
• Needle length: >1 inch (25mm) for most adults to ensure proper penetration into muscle tissue 2
• Volume: 0.5 mL for persons ≥3 years (36 months) 1

For Infants and Young Children:

• Recommended site: Anterolateral aspect of the thigh 1
• Needle length: 7/8-1 inch (22-25mm) for children <12 months 2
• Volume: 0.25 mL for infants and toddlers 6-35 months of age 1

Why the Buttocks Should Be Avoided

Administering influenza vaccine in the buttocks is problematic for several reasons:

1. Reduced immunogenicity: Injection into gluteal fat rather than muscle can lead to suboptimal immune response
2. Risk of sciatic nerve injury: The gluteal area contains the sciatic nerve which could be injured during injection
3. Inconsistent absorption: The buttocks often have more subcutaneous fat, leading to variable vaccine absorption

Special Considerations

• Intradermal formulation: Some influenza vaccines (like Fluzone Intradermal Quadrivalent) are administered intradermally, preferably over the deltoid muscle, using a specialized delivery system 1
• Jet injector administration: Certain IIVs (Afluria and Afluria Quadrivalent) are licensed for intramuscular administration via jet injector for persons aged 18-64 years 1
• Body mass considerations: Healthcare providers should consider patient factors such as body mass index and subcutaneous tissue thickness when selecting needle length 2

Common Pitfalls to Avoid

1. Splitting doses: A 0.5-mL unit dose of any IIV should never be split into two separate 0.25-mL doses due to safety concerns, including lack of sterility 1
2. Inadequate needle length: Using needles that are too short (<1 inch) for adults may result in subcutaneous rather than intramuscular administration, potentially reducing vaccine effectiveness 2
3. Using expired vaccines: Previous season's vaccines should not be used for the current influenza season 1

Following these evidence-based administration guidelines will help ensure optimal vaccine effectiveness and minimize adverse events.