When should rabies vaccines be administered after exposure to the virus?

Rabies Vaccine Administration Timing

Rabies post-exposure prophylaxis (PEP) must be administered as soon as possible after exposure, ideally within 24 hours, though it can still be beneficial when administered at any time before symptom onset due to the typically long incubation period of 1-3 months. 1

Post-Exposure Prophylaxis Regimens

For Previously Unvaccinated Individuals:

• Standard 4-dose regimen: 1.0 mL intramuscular injections on days 0,3,7, and 14 2, 1
  • Day 0 = day of first vaccine dose (should be as soon as possible after exposure)
  • Administered in the deltoid muscle for adults/older children or anterolateral thigh for younger children
  • Avoid gluteal area due to reduced efficacy 1

For Immunocompromised Patients:

• 5-dose regimen: 1.0 mL intramuscular injections on days 0,3,7,14, and 28 1
• Serologic testing recommended to confirm adequate antibody response 1

For Previously Vaccinated Individuals:

• 2-dose regimen: 1.0 mL intramuscular injections on days 0 and 3 only 2, 1
• No rabies immunoglobulin (RIG) required 1, 3

Essential Components of PEP

1. Wound Cleansing:

   • Thoroughly wash with soap and water for at least 15 minutes 1, 4
   • Use povidone-iodine solution if available 1

2. Rabies Immunoglobulin (RIG):

   • Administer 20 IU/kg body weight 1
   • Infiltrate full dose around and into all wounds if anatomically feasible
   • Any remaining volume should be administered intramuscularly at a site distant from vaccine administration 1, 3
   • Do not administer to previously vaccinated persons 1, 3
   • Can be administered up to and including day 7 if not given at initiation of PEP 3

3. Rabies Vaccine:

   • Follow appropriate dosing schedule based on vaccination history (as outlined above)

Effectiveness and Important Considerations

• PEP is nearly 100% effective in preventing rabies when administered correctly 1, 5
• Even if initiation of treatment is delayed, still administer RIG and vaccine regardless of the interval between exposure and treatment 3
• The value of immediate passive immunization with RIG cannot be overemphasized 3
• Common errors that reduce effectiveness include:
  • Delayed initiation
  • Incomplete vaccination
  • Failure to properly infiltrate wounds with RIG
  • Improper injection site
  • Inadequate wound cleansing 1

Risk Assessment

Healthcare providers must evaluate each possible rabies exposure considering:

1. Species of biting animal (bats, wild terrestrial carnivores, domestic animals)
2. Circumstances of biting incident (provoked vs. unprovoked)
3. Type of exposure (bite vs. nonbite)
4. Vaccination status of biting animal 3

When in doubt about the need for treatment, consult local or state public health officials 3.

Human rabies is nearly 100% fatal if prophylactic measures are not followed correctly, making timely and appropriate administration of PEP critical 5.

Human-to-human transmission is extremely rare but has occurred through organ transplantation 3, 5.

Human rabies immune globulin (RIG) is in limited supply and may be replaced by monoclonal antibodies in the future due to potential advantages in supply, cost, and efficacy 6.

Pre-Exposure Prophylaxis

For individuals at high risk of exposure (laboratory workers, veterinarians, animal control workers, etc.):

• 3-dose regimen: administered on days 0,7, and 21 or 28 2, 1
• Simplifies subsequent PEP if exposure occurs 5

Human rabies is nearly 100% fatal once clinical symptoms appear, making proper and timely PEP administration essential for preventing death 5, 4.