Can the rabies vaccine be administered intramuscularly (IM) and then switched to intradermally (ID)?

Rabies Vaccine Administration Route Switching

Rabies vaccine administration should not be switched from intramuscular (IM) to intradermal (ID) route during a vaccination series, as there are no specific guidelines supporting this practice and consistency in administration route is recommended throughout the complete vaccination series.

Standard Rabies Vaccination Protocols

The Advisory Committee on Immunization Practices (ACIP) provides clear guidance on rabies vaccination administration:

Post-Exposure Prophylaxis (PEP)

• For previously unvaccinated persons: A 4-dose regimen of rabies vaccine administered intramuscularly on days 0,3,7, and 14 1
• For previously vaccinated persons: 2 doses of vaccine (1.0 mL each) administered intramuscularly on days 0 and 3 1
• For immunocompromised persons: 5-dose regimen on days 0,3,7,14, and 28 1

Pre-Exposure Prophylaxis

• Standard regimen: 3 doses administered on days 0,7, and 21 or 28 1, 2
• Administration routes:
  • Intramuscular (IM): 1.0 mL per dose for all vaccine types
  • Intradermal (ID): 0.1 mL per dose, but ONLY approved for HDCV (Imovax Rabies I.D.) 1

Route-Specific Considerations

Intramuscular Administration

• Recommended site: Deltoid area for adults and older children; anterolateral thigh for younger children 1
• Never use the gluteal area as it results in lower neutralizing antibody titers 1
• All licensed rabies vaccines in the US can be administered via IM route 1

Intradermal Administration

• Only HDCV (Imovax Rabies I.D.) is FDA-approved for intradermal administration 1
• RVA and PCEC should not be used intradermally 1
• Special considerations for ID administration include interference by antimalarial drugs like chloroquine and mefloquine 1

Switching Administration Routes

While research suggests that rabies vaccines can be immunogenic by both IM and ID routes 3, 4, there is no specific guidance in the ACIP recommendations or other authoritative guidelines supporting switching routes during a vaccination series. In fact, the guidance implies maintaining consistency:

• "Usually, an immunization series is initiated and completed with one vaccine product" 1
• The guidelines provide separate, complete regimens for each route rather than mixed approaches

Research on Interchangeability

Limited research has examined interchangeability of rabies vaccines:

• A study of 90 animal bite cases showed that changes in route of administration (from IM to ID or vice versa) did not compromise safety or immunogenicity 5
• However, this represents an exception rather than a recommended practice

Best Practice Recommendations

1. Maintain consistency in administration route throughout the complete vaccination series
2. Complete the series as started - if initiated with IM administration, continue with IM for all doses
3. If route switching is unavoidable due to logistical or supply issues, consult with public health authorities and ensure adequate antibody response through serologic testing
4. For travelers who may need antimalarial medications, avoid ID administration due to potential interference 1, 2

Common Pitfalls to Avoid

• Improper administration site: Always use deltoid for adults (never gluteal area)
• Incorrect dosing: 1.0 mL for IM versus 0.1 mL for ID administration
• Using inappropriate vaccine for ID: Only HDCV is approved for ID administration
• Incomplete vaccination series: All doses must be administered according to schedule
• Antimalarial interference: Avoid ID administration for persons taking chloroquine or mefloquine

In summary, while limited research suggests that switching routes may not compromise immunogenicity, the established guidelines recommend maintaining consistency in administration route throughout the vaccination series to ensure optimal protection against rabies.