Antirabies Booster Dosing
For routine preexposure booster vaccination in previously immunized individuals, a single dose is required, administered either as 1.0 mL intramuscularly or 0.1 mL intradermally. 1
Context-Specific Booster Recommendations
Routine Preexposure Booster (No Recent Exposure)
One single dose is sufficient for routine booster vaccination in previously vaccinated individuals. 1 This can be administered as:
- 1.0 mL intramuscularly in the deltoid area, OR
- 0.1 mL intradermally over the deltoid region 1
The frequency of this single-dose booster depends on your occupational risk category:
- Continuous risk (laboratory workers handling live rabies virus): Check antibody titers every 6 months and give a single booster dose when titers fall below 1:5 neutralization 1, 2
- Frequent risk (veterinarians, animal control officers in endemic areas): Check titers every 2 years and give a single booster dose if inadequate, or give booster without testing 1, 2
- Infrequent risk (veterinarians in low-rabies areas, travelers): No routine boosters needed after primary series completion 1, 2
Postexposure Booster (After Potential Rabies Exposure)
If you have been previously vaccinated and are now exposed to rabies, you need exactly two doses: one immediately (day 0) and one on day 3. 1, 3, 4, 5 Each dose is 1.0 mL administered intramuscularly in the deltoid. 1, 4, 5
Critical: Do NOT administer rabies immunoglobulin (RIG) to previously vaccinated persons—it will inhibit the anamnestic antibody response. 1, 3, 4, 5
Important Caveats and Pitfalls
Definition of "Previously Vaccinated"
You are considered previously vaccinated if you have received:
- A complete preexposure prophylaxis regimen (3 doses) of HDCV, RVA, or PCEC, OR
- A complete postexposure prophylaxis regimen, OR
- Any other rabies vaccine with documented rabies antibody titer 1, 4
Immunosuppressed Patients Exception
Immunosuppressed individuals require special management and should receive the full 5-dose series (days 0,3,7,14,28) even if previously vaccinated, with mandatory antibody titer testing 7-14 days after completion. 3, 4 This is a critical exception to the two-dose rule for postexposure prophylaxis.
Antimalarial Drug Interaction
Avoid intradermal administration if the patient is taking chloroquine or structurally related antimalarials (e.g., mefloquine), as these drugs decrease antibody response to HDCV. 1 Use the intramuscular route instead, or complete the intradermal series at least 1 month before starting antimalarial prophylaxis. 1
Timing Flexibility
Delays of a few days between doses are acceptable and do not require restarting the series. 3 If you miss a dose, resume the schedule without restarting—just continue from where you left off. 3
RIG Administration Window
If RIG was not given initially in an unvaccinated person receiving postexposure prophylaxis, it can be administered up to and including day 7 of the vaccine series, but never after day 7, as it may suppress active antibody production. 3, 5