What is the protocol for post-exposure prophylaxis (PEP) for rabies exposure?

Rabies Post-Exposure Prophylaxis Protocol

For previously unvaccinated individuals exposed to rabies, immediately initiate a 4-dose vaccine regimen (days 0,3,7, and 14) combined with rabies immune globulin (RIG) at 20 IU/kg on day 0, along with thorough wound washing—this protocol is nearly 100% effective when administered promptly. 1, 2

Immediate Wound Care (First Priority)

• Thoroughly wash all wounds with soap and water for 15 minutes immediately after exposure—this is the single most effective initial measure for preventing rabies infection and must be done before any other intervention. 1, 2, 3
• If available, irrigate wounds with a virucidal agent such as povidone-iodine solution after washing. 4, 5
• Administer tetanus prophylaxis and antibiotics as indicated for bacterial infection control. 3, 5

Risk Assessment Before Initiating PEP

High-Risk Exposures (Initiate PEP Immediately)

• Bats: Any physical contact with bats when bite, scratch, or mucous membrane contact cannot be excluded requires PEP, as bat bites may be minor and difficult to recognize. 5
• Wild carnivores (raccoons, skunks, foxes): All bites should be considered rabies exposures and PEP initiated immediately unless the animal is available for expeditious laboratory testing or brain tissue has already tested negative. 5
• Rabid or suspected rabid domestic animals (dogs, cats, ferrets): Begin PEP immediately. 3, 5

Lower-Risk Exposures (Observation or Consultation)

• Healthy domestic dogs, cats, ferrets available for 10-day observation: Do not begin PEP unless the animal develops clinical signs of rabies during observation. 3, 5
• Small rodents (squirrels, hamsters, guinea pigs, rats, mice) and lagomorphs (rabbits, hares): Almost never require PEP; consult local health department. 5

Vaccine Regimen for Previously Unvaccinated Persons

• Administer 4 doses of rabies vaccine (HDCV or PCECV) at 1.0 mL intramuscularly on days 0,3,7, and 14. 1, 2
• Inject in the deltoid muscle for adults and older children; use the anterolateral thigh for young children. 2, 6
• Never administer vaccine in the gluteal area—this produces inadequate antibody response and has been associated with PEP failures. 2
• This represents a reduction from the historical 5-dose schedule, as evidence demonstrates that 4 doses in combination with RIG elicit adequate immune responses without need for a fifth dose. 1, 4

Rabies Immune Globulin (RIG) Administration

• Administer RIG at 20 IU/kg body weight on day 0, ideally at the same time as the first vaccine dose. 2, 4, 5
• Infiltrate the full dose of RIG around and into all wounds if anatomically feasible; administer any remaining volume intramuscularly at a site distant from vaccine administration. 2, 6, 5
• Do not administer RIG in the same syringe or at the same anatomical site as the vaccine, as this may interfere with vaccine immunogenicity. 2, 4, 5
• Do not exceed the recommended 20 IU/kg dose, as excessive amounts may partially suppress active antibody production. 4
• If RIG was not administered on day 0, it can still be given up to and including day 7 of the vaccine series. 1, 5

Previously Vaccinated Persons (Simplified Regimen)

• Administer only 2 doses of vaccine (days 0 and 3) without RIG for persons who previously received a complete vaccination series with cell-culture vaccine or who have documented adequate rabies virus-neutralizing antibody titers. 1, 6
• Do not administer RIG to previously vaccinated persons, as it can inhibit the expected rapid anamnestic immune response. 1, 6
• Local wound care remains essential for all previously vaccinated persons. 1

Immunocompromised Patients (Extended Regimen)

• Use a 5-dose vaccine regimen (days 0,3,7,14, and 28) plus RIG at 20 IU/kg for all immunocompromised individuals, even if previously vaccinated. 1, 2, 4
• Corticosteroids, other immunosuppressive agents, antimalarials, and immunosuppressive illnesses may substantially reduce immune responses to rabies vaccines. 1
• Obtain serologic testing 7-14 days after the final dose to confirm adequate antibody response (≥0.5 IU/mL or complete virus neutralization at 1:5 dilution by RFFIT). 1, 2, 4
• If no acceptable antibody response is detected, manage in consultation with public health officials. 3

Critical Timing Considerations

• Initiate PEP as soon as possible after exposure—delays of even hours matter significantly because rabies is nearly 100% fatal once clinical symptoms develop. 2, 6
• There is no absolute cutoff beyond which PEP should be withheld—treatment should begin immediately upon recognition of exposure, even if weeks or months have elapsed, provided the exposed person shows no clinical signs of rabies. 1, 2, 4
• Administration of PEP is a medical urgency, not a medical emergency, but decisions must not be delayed. 1

Post-Vaccination Serologic Testing

• Routine serologic testing is not necessary for immunocompetent individuals completing PEP according to guidelines, as all healthy persons demonstrate adequate antibody response. 1, 6
• For immunosuppressed patients, obtain serum specimens 1-2 weeks after the final vaccine dose to document adequate antibody response. 1, 2
• Acceptable antibody response is complete virus neutralization at a 1:5 serum dilution by RFFIT. 1

Common Pitfalls to Avoid

• Never delay wound washing while arranging for vaccine and RIG—immediate thorough cleansing is critical. 2, 7
• Do not withhold PEP due to cost concerns—rabies is nearly 100% fatal without prophylaxis, making PEP cost-effective despite expense. 4
• Do not discontinue PEP prematurely unless laboratory testing (direct fluorescent antibody test) confirms the exposing animal was not rabid. 3, 5
• Consult local or state health departments for guidance on unclear exposures or when questions arise about the need for prophylaxis. 1, 3, 5