How many rabies (Rabies Immunization) vaccine doses are needed for post-exposure prophylaxis (PEP) after a dog bite?

Rabies Post-Exposure Prophylaxis After Dog Bite

For previously unvaccinated individuals, administer 4 doses of rabies vaccine intramuscularly on days 0,3,7, and 14, combined with rabies immune globulin (RIG) at 20 IU/kg on day 0. 1, 2

Standard PEP Regimen for Previously Unvaccinated Persons

The current CDC/ACIP recommendation represents a reduction from the older 5-dose schedule, making treatment more practical while maintaining near 100% efficacy when properly administered 1, 2:

• Vaccine schedule: 4 intramuscular doses of 1.0 mL each on days 0,3,7, and 14 (day 0 is when the first dose is given, not necessarily the exposure date) 3, 1, 4
• RIG administration: 20 IU/kg body weight given once on day 0, ideally simultaneously with the first vaccine dose 3, 1, 2
• RIG infiltration technique: The full calculated dose should be thoroughly infiltrated around and into the wound(s) if anatomically feasible; any remaining volume is injected intramuscularly at a site distant from vaccine administration 3, 1, 4

Critical Administration Details

Injection sites matter significantly for vaccine efficacy:

• Administer vaccine in the deltoid muscle for adults and older children 3, 1, 2
• Use the anterolateral thigh for young children 3, 1, 2
• Never use the gluteal area - this produces inadequate antibody response and has been associated with vaccine failures 3, 1, 2

RIG administration pitfalls to avoid:

• Do not administer RIG in the same syringe or at the same anatomical site as the vaccine 3, 1, 2
• Do not exceed 20 IU/kg dose, as higher amounts suppress active antibody production 3, 1
• RIG can be given up to and including day 7 if not administered initially, but beyond day 7 it should not be given as vaccine-induced antibody response is presumed to have occurred 3, 1

Immediate Wound Management

Before any biologicals are administered, thoroughly wash all wounds with soap and water for 15 minutes - this single intervention markedly reduces rabies risk in animal studies and may be the most effective preventive measure 3, 1, 5

Modified Regimens for Special Populations

Previously vaccinated persons (those who completed a prior pre-exposure or post-exposure series with cell culture vaccine):

• Require only 2 doses of vaccine on days 0 and 3 3, 1, 6, 2
• Do NOT receive RIG - it will inhibit the anamnestic antibody response 3, 1, 2

Immunocompromised patients (on corticosteroids, other immunosuppressives, or with conditions like HIV):

• Require the 5-dose regimen on days 0,3,7,14, and 28 plus RIG at 20 IU/kg 1, 2, 4
• Must have serologic testing 1-2 weeks after the final dose to confirm adequate antibody response 1
• This applies even if previously vaccinated, as immunosuppression substantially reduces vaccine response 1

Timing Considerations

Initiate PEP as soon as possible after exposure, ideally within 24 hours 3, 1, 2. However, there is no absolute cutoff - treatment should begin immediately upon recognition of exposure even if weeks or months have elapsed, as rabies incubation periods can exceed one year and the disease is uniformly fatal once symptoms appear 3, 1, 6.

Common Clinical Pitfalls

• Do not withhold treatment while waiting for animal observation results if the exposure occurred in a rabies-endemic area - treatment can be discontinued if the animal remains healthy after 10 days 3
• Do not delay treatment for serologic testing in previously unvaccinated persons - routine post-vaccination antibody testing is unnecessary in immunocompetent individuals 3, 4
• Do not give RIG to previously vaccinated persons - this is a critical error that suppresses the memory immune response 3, 1, 2
• Children receive the same vaccine volume (1.0 mL) and RIG dose (20 IU/kg) as adults - do not reduce doses 1, 2