What is the difference between a 3-dose and 4-dose regimen of Intradermal Rabies Vaccine (IDRV) 0.1ml?

Intradermal Rabies Vaccine: 4-Dose vs 3-Dose Regimen

The standard recommended regimen for intradermal rabies vaccine (IDRV) 0.1ml is the 4-dose schedule administered on days 0,3,7, and 14, which has been proven safe and effective for post-exposure prophylaxis in immunocompetent individuals. 1, 2, 3

Standard Post-Exposure Prophylaxis Regimen

• The Advisory Committee on Immunization Practices (ACIP) recommends a 4-dose vaccine schedule for previously unvaccinated individuals as part of rabies post-exposure prophylaxis 1, 2, 4
• The 4-dose schedule consists of vaccine administration on days 0,3,7, and 14, with day 0 being the day the first dose is administered 1, 5
• This regimen has replaced the previous 5-dose schedule (days 0,3,7,14, and 28) based on evidence of adequate immunogenicity and effectiveness 1, 4
• When used appropriately with timely wound care and administration of human rabies immune globulin (HRIG), the 4-dose vaccine schedule induces an adequate, long-lasting antibody response 4

Special Considerations for Immunocompromised Patients

• For persons with immunosuppression, rabies PEP should still be administered using a 5-dose vaccine regimen (days 0,3,7,14, and 28) 1, 5
• Immunosuppressive agents, antimalarials, and immunosuppressive illnesses might reduce immune responses to rabies vaccines substantially 1
• When rabies post-exposure prophylaxis is administered to an immunosuppressed person, serum samples should be tested for rabies virus-neutralizing antibody to ensure an acceptable antibody response 1, 2

Administration Considerations

• The deltoid area is the only acceptable site of vaccination for adults and older children; for younger children, the outer aspect of the thigh may be used 1
• Vaccine should never be administered in the gluteal area as this can result in diminished immunologic response 1, 5
• Human rabies immune globulin (HRIG) should be administered at 20 IU/kg body weight for previously unvaccinated individuals, with the full dose infiltrated around and into the wound(s) if anatomically feasible 2, 3
• Any remaining volume of HRIG should be injected intramuscularly at a site distant from vaccine administration 1

Differences Between 3-Dose and 4-Dose Regimens

• The 3-dose regimen is not currently recommended by the ACIP for post-exposure prophylaxis in the United States 1, 2
• The 4-dose regimen has been extensively studied and shown to be safe and effective while providing cost savings to the healthcare system 3, 4
• The 4-dose schedule was adopted based on evidence that most rabies PEP failures occurred before day 28 when the fifth dose would have been administered 5
• All healthy persons tested in accordance with ACIP guidelines after completion of at least a 4-dose regimen of rabies PEP should demonstrate an adequate antibody response against rabies virus 1

Previously Vaccinated Individuals

• Previously vaccinated persons require only 2 doses of vaccine (on days 0 and 3) and do not need HRIG administration 1, 5
• Previously vaccinated persons are those who have received one of the ACIP-recommended pre- or postexposure prophylaxis regimens or those who received another vaccine regimen and had a documented adequate rabies virus-neutralizing antibody response 1

Common Pitfalls to Avoid

• Delaying initiation of PEP: Rabies post-exposure prophylaxis should be started as soon as possible after exposure 3, 6
• Administering vaccine in the gluteal area, which can result in diminished immune response 1, 5
• Using more than the recommended dose of HRIG, which can suppress active antibody production 3, 5
• Failing to infiltrate HRIG around the wound when anatomically feasible 3, 5
• Incomplete vaccination: Every effort should be made to complete the full vaccination schedule 3, 7