What is the recommended dose and administration schedule for the rabies Intramuscular (IM) vaccine?

Rabies IM Vaccine Dose

For previously unvaccinated individuals exposed to rabies, administer 1.0 mL of rabies vaccine intramuscularly on days 0,3,7, and 14, combined with human rabies immune globulin (HRIG) at 20 IU/kg on day 0. 1, 2, 3

Vaccine Dosing and Administration

Standard Dose for Post-Exposure Prophylaxis (Previously Unvaccinated)

• Each dose is 1.0 mL administered intramuscularly using either human diploid cell vaccine (HDCV) or purified chick embryo cell vaccine (PCECV) 1, 3
• Schedule: Days 0,3,7, and 14 (day 0 is the day the first dose is given, not necessarily the exposure date) 1, 2, 4
• This 4-dose regimen replaced the older 5-dose schedule in 2009 based on strong evidence showing equivalent efficacy when combined with HRIG 5, 6

Injection Site Selection

• Adults and older children: Deltoid muscle only 1, 3
• Young children: Anterolateral thigh 1, 3
• Never use the gluteal area - this produces inadequate antibody titers and has been associated with vaccine failures 1, 2

HRIG Administration (Critical Component)

• Dose: 20 IU/kg body weight, given once on day 0 1, 4, 3
• Infiltrate as much as anatomically possible into and around the wound(s), with any remaining volume given IM at a site distant from the vaccine 1, 3
• Can be given up to day 7 if not administered initially, but is not indicated beyond day 7 as antibody response to vaccine is presumed 1, 7
• Never administer in the same syringe or anatomical site as the vaccine 1, 4, 3
• Do not exceed the recommended dose as this suppresses active antibody production 1, 4

Modified Regimens for Special Populations

Previously Vaccinated Individuals

• Only 2 doses needed: 1.0 mL IM on days 0 and 3 1, 4
• No HRIG required - it will inhibit the anamnestic response 1, 4
• This applies to anyone who completed a prior ACIP-recommended pre- or post-exposure series with cell-culture vaccines 4

Immunocompromised Patients

• Use the 5-dose regimen: Days 0,3,7,14, and 28 2, 4, 6
• Still give HRIG at 20 IU/kg on day 0, even if previously vaccinated 2, 4
• The standard 4-dose schedule is inadequate for this population 2

Pediatric Patients

• Same dose volume as adults: 1.0 mL per dose 4, 3
• Same HRIG dose: 20 IU/kg 4, 3
• Use anterolateral thigh for vaccine administration in young children 1, 4

Pre-Exposure Prophylaxis Dosing

• Three 1.0 mL IM doses on days 0,7, and 21 or 28 1
• Alternative intradermal regimen: 0.1 mL ID doses on days 0,7, and 21 or 28 (HDCV only, not approved for other vaccines) 1
• Do not use intradermal route if patient is taking chloroquine or mefloquine - these antimalarials interfere with immune response 1

Critical Timing and Schedule Adherence

• Initiate as soon as possible after exposure, ideally within 24 hours 2, 4
• No absolute cutoff - treatment should begin regardless of time elapsed since exposure, as rabies is nearly 100% fatal once symptomatic 2, 4
• Minor delays of a few days are unimportant, but for substantial deviations, check serologic titers 7-14 days after the final dose 1, 7
• If a dose is missed, give it immediately when the patient presents and resume the schedule maintaining the same intervals 7

Essential Wound Care

• Immediately wash all wounds with soap and water for 15 minutes - this is the single most effective measure for preventing rabies 2, 4
• Follow with irrigation using a virucidal agent like povidone-iodine if available 4, 3

Common Pitfalls to Avoid

• Never use gluteal injection site - associated with vaccine failure 1, 2, 4
• Never give HRIG to previously vaccinated persons - it inhibits the immune response 1, 4
• Never mix HRIG and vaccine in the same syringe or inject at the same site 1, 4, 3
• Never exceed 20 IU/kg of HRIG - higher doses suppress antibody production 4, 3
• Don't forget to upgrade immunocompromised patients to the 5-dose regimen 2, 4