Animal Bite Vaccine Dosing Regimen
Primary Recommendation
For previously unvaccinated patients bitten by animals, administer both rabies immune globulin (HRIG) at 20 IU/kg and a 4-dose rabies vaccine series (days 0,3,7,14) immediately, while previously vaccinated patients require only a 2-dose vaccine booster (days 0,3) without HRIG. 1, 2, 3
Immediate Wound Management (All Patients)
- Thoroughly wash the wound with soap and water for 15 minutes immediately - this is the single most effective measure for preventing rabies and markedly reduces infection risk 2, 4
- Apply povidone-iodine solution or similar virucidal agent to the wound site if available 2
- Assess tetanus prophylaxis needs based on immunization status 1, 2
- Avoid suturing wounds when possible, as this may increase rabies risk 1
Vaccination Algorithm Based on Prior Vaccination History
For Previously UNVACCINATED Patients (Never Received Rabies Vaccine)
Standard Regimen (Immunocompetent):
- Administer HRIG at 20 IU/kg body weight once on day 0 1, 3
- Administer rabies vaccine (HDCV or PCECV) on days 0,3,7, and 14 (4-dose schedule) 2, 3
- Inject vaccine in the deltoid muscle in adults or anterolateral thigh in children - never in the gluteal area, as this results in lower antibody titers and has been associated with prophylaxis failures 2, 3
Modified Regimen (Immunocompromised Patients):
- Use a 5-dose vaccine regimen on days 0,3,7,14, and 28 plus HRIG 3
- This extended schedule ensures adequate antibody response in patients with impaired immune function 3
For Previously VACCINATED Patients (Completed Prior Pre- or Post-Exposure Series)
- Administer vaccine only - do NOT give HRIG 1, 2, 3
- Use 2-dose schedule: day 0 and day 3 2, 3
- This simplified regimen is effective because previously vaccinated individuals develop a rapid anamnestic (memory) immune response 3
Critical Timing Considerations for HRIG
- HRIG can be administered up to and including day 7 of the postexposure prophylaxis series if not given initially 1, 2, 3
- Beyond day 7, HRIG is NOT indicated because vaccine-induced antibody response is presumed to have occurred 1, 2, 3
- HRIG can partially suppress active antibody production, so the dose should never exceed 20 IU/kg 1, 3
- Begin treatment immediately after exposure (within 24 hours ideally), though even delayed treatment is indicated as rabies incubation periods can exceed 1 year 2, 3
Common Pitfalls to Avoid
- Never administer more than 20 IU/kg of HRIG - excess doses may suppress active antibody production 2, 3
- Never inject rabies vaccine in the gluteal area - use deltoid in adults or anterolateral thigh in children to ensure adequate antibody response 2, 3
- Never administer HRIG in the same syringe or anatomical site as the first vaccine dose 1
- Do not give HRIG to previously vaccinated patients, as it is unnecessary and may interfere with the anamnestic response 1, 2
- Do not delay treatment waiting for animal observation results if the animal cannot be captured - initiate prophylaxis immediately and discontinue only if laboratory testing proves the animal was not rabid 1
Special Considerations
Re-exposure Within 6 Months:
- Patients re-exposed within 6 months of completing a full PEP series require only 2 vaccine doses (days 0 and 3) without HRIG 3
Treatment Regardless of Delay:
- PEP should be initiated regardless of the interval from exposure, even if many months have passed, as long as clinical rabies symptoms have not appeared 3
- Once clinical symptoms develop, rabies is universally fatal with no effective treatment 5
Antibody Monitoring:
- While routine antibody titer checking is not required for standard post-exposure prophylaxis, research suggests that antibody levels may wane over time, with only 70% of fully vaccinated individuals maintaining protective titers after one year 6
- This supports the recommendation for re-vaccination upon re-exposure rather than relying on prior vaccination alone 6