What is the recommended rabies vaccine (Rabies Immunization) protocol for previously vaccinated individuals exposed to rabies?

Rabies Vaccine Protocol for Previously Vaccinated Individuals

Previously vaccinated individuals exposed to rabies should receive two intramuscular doses (1.0 mL each) of rabies vaccine, one immediately and one 3 days later, without rabies immunoglobulin. 1

Definition of "Previously Vaccinated"

Previously vaccinated refers to persons who have:

• Received one of the recommended preexposure or postexposure regimens of HDCV (Human Diploid Cell Vaccine), PCECV (Purified Chick Embryo Cell Vaccine), or RVA (Rabies Vaccine Adsorbed) 1
• OR received another rabies vaccine and have a documented rabies virus neutralizing antibody titer 1

Postexposure Protocol for Previously Vaccinated Individuals

Required Components:

1. Local wound care:

   • Immediate and thorough cleansing of all wounds with soap and water 2
   • This simple measure markedly reduces the likelihood of rabies infection 2

2. Vaccine administration:

   • Two IM doses (1.0 mL each) in the deltoid muscle 1
   • First dose: immediately upon presentation 1
   • Second dose: 3 days after the first dose 1

3. Rabies Immunoglobulin (RIG):

   • NOT indicated for previously vaccinated individuals 1
   • Should NOT be administered as it may inhibit the strength or rapidity of the expected anamnestic immune response 1

Rationale for Modified Protocol

• Previously vaccinated individuals develop a rapid anamnestic antibody response following booster vaccination, regardless of their pre-booster antibody titer 1
• This immune memory response eliminates the need for rabies immunoglobulin and the full vaccination series 1
• The two-dose regimen has been shown to produce adequate antibody levels in previously vaccinated individuals 3

Important Considerations

No Need for Serologic Testing Before Boosters

• For previously vaccinated persons exposed to rabies, determining the rabies virus neutralizing antibody titer before administering boosters is unnecessary and inappropriate for several reasons 1:
  • It would delay treatment while waiting for test results
  • No specific "protective" titer is definitively established
  • Cell-mediated immunity also plays a role in protection, not just antibody levels 1

Long-term Immunity

• Studies show that 57.8-62.0% of individuals maintain adequate rabies virus neutralizing antibody concentrations (≥0.5 IU/mL) for up to 10 years after primary vaccination 4
• A single booster dose after primary vaccination confers high and long-term immune response in nearly all individuals 5

Special Populations

• Immunosuppressed individuals require special consideration:
  • They may have suboptimal response to vaccination 1
  • Consider consultation with public health officials if treating an immunosuppressed previously vaccinated individual 1

Common Pitfalls to Avoid

1. Administering rabies immunoglobulin to previously vaccinated individuals:

   • This is contraindicated and may interfere with the anamnestic response 1

2. Delaying treatment to check antibody titers:

   • This creates unnecessary delay in a time-sensitive situation 1
   • Postexposure prophylaxis should be initiated promptly (within 24 hours if possible) 2

3. Using the wrong administration site:

   • Vaccines should be administered in the deltoid muscle, not the gluteal area 1

4. Confusing preexposure booster protocols with postexposure protocols:

   • Preexposure boosters follow different schedules based on risk category 1
   • Postexposure management for previously vaccinated individuals is standardized as the two-dose regimen 1