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# Antirabies Vaccine
## Overview
Rabies vaccine is an inactivated virus preparation used for pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP). Two common formulations are Human Diploid Cell Vaccine (HDCV) and Purified Chick Embryo Cell Vaccine (PCECV).
## Primary Indications
* **Pre-exposure prophylaxis:** High-risk occupational groups (e.g., veterinarians, laboratory workers, spelunkers).
* **Post-exposure prophylaxis:** Following exposure to a rabid or potentially rabid animal (e.g., bite, scratch, or mucous membrane exposure).
## Adult Dosing
* **Pre-exposure Prophylaxis (PrEP):** 1 mL intramuscularly (IM) in the deltoid on days 0 and 7.
* **Post-exposure Prophylaxis (PEP):**
* *Previously immunized:* 1 mL IM on days 0 and 3. No Rabies Immune Globulin (RIG) is required.
* *Unvaccinated:* 1 mL IM on days 0, 3, 7, and 14. RIG (20 IU/kg) should be administered on day 0, infiltrated around the wound site.
## Pediatric Dosing
* **Dosing:** Same as adult dosage (1 mL IM).
* **Anatomic Site:** For children <1 year, use the anterolateral thigh. For children ≥1 year, use the deltoid. Never administer the vaccine in the gluteal region.
## Dose Adjustments
* **Immunocompromised patients:** For PEP, a 5th dose on day 28 is required for immunocompromised individuals. Pre-exposure prophylaxis may require serologic monitoring to ensure adequate titer response.
* **Weight-based:** No adjustment, but RIG dose is strictly weight-based (20 IU/kg).
## Contraindications
* **Pre-exposure:** History of a severe allergic reaction (anaphylaxis) to a previous dose or vaccine component.
* **Post-exposure:** There are **no contraindications** for PEP, as rabies is universally fatal. If a systemic allergic reaction occurs, manage with antihistamines/epinephrine and complete the series.
## Adverse Effects
* **Common:** Injection site pain, erythema, swelling, itching, lethargy, headache, or mild fever.
* **Rare:** Serum sickness-like reaction (usually 7–10 days after booster doses), Guillain-Barré syndrome (very rare).
## Key Drug Interactions
* **Immunosuppressants/Corticosteroids:** May interfere with the immune response to the vaccine. Avoid until the series is complete if possible.
* **Rabies Immune Globulin:** Must be administered only at the start of PEP (day 0) and never mixed in the same syringe or same anatomical site as the vaccine.
## Monitoring
* **Titer checks:** Required for high-risk category 3 individuals (e.g., laboratory workers) every 6 months to ensure levels remain above 0.5 IU/mL.
* **Adverse events:** Monitor for immediate hypersensitivity for 15–30 minutes post-injection.
## Clinical Pearls
* **Wound Care:** Crucial first step is thorough irrigation and cleaning with soap and water or povidone-iodine.
* **Site Selection:** Always use the deltoid muscle for adults; gluteal injections are associated with treatment failure due to poor absorption.
* **Local Policies:** Always consult local health department protocols or the CDC "Green Book" for specific regional variations in PEP schedules or current requirements for pre-exposure booster intervals.
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**Educational Disclaimer:** This information is for educational purposes only. Always consult the most recent product labeling, current CDC guidelines, and your institutional protocols before prescribing or administering medication. Clinical practice is subject to change.
