Rabies Vaccine & HRIG Administration Guide

Post exposure prophylaxis (PEP) guide, human rabies immune globulin (HRIG), how to calculate/split HRIG dosing across wounds and IM sites, with documentation tips. Includes a dose calculator.
Calculator

HRIG Dose & Per-Site Split

Formula: 20 IU/kg (all ages) once at PEP initiation (Day 0), or up to Day 7 after first vaccine dose if missed.

Key Points

When to Start & Why Separate HRIG/Vaccine

  • Start PEP promptly when risk is meaningful or animal testing/observation will be delayed; you may discontinue if the animal tests negative.
  • Vaccine may be started any time post-exposure if the patient remains asymptomatic.
  • HRIG 20 IU/kg once, ideally Day 0; can be given through Day 7 after first vaccine dose, not after.
  • Bat exposures with uncertain bite: give PEP; if no wound to infiltrate, give full HRIG dose IM distant from vaccine.
  • Separation: HRIG can neutralize vaccine antigen if colocated—use different anatomic sites; never mix in the same syringe/site.
  • Gluteal: Do not administer vaccine in the gluteal region. For HRIG, prefer deltoid/thigh to avoid sciatic risk; if used, ensure proper landmarking and depth.
Documentation: Record animal status/consults, wound care, vaccine product/lot/site, HRIG product/strength, total IU/mL, volumes per wound, dilution (if any), and IM remainder sites.
Quick Reference

Site Capacity & Needle Selection

  • Practical IM site capacities (adults): Deltoid ~0.5–2 mL; Vastus lateralis ~1–5 mL (split larger volumes).
  • Needles: 22–25G; length 1–1.5" for most teens/adults; choose to ensure intramuscular depth.
  • No wound to infiltrate? Give the full HRIG dose IM, split across large muscles distant from vaccine.
  • Dilution for infiltration volume: CDC allows NS; HyperRAB 300 IU/mL label specifies use D5W if dilution is required.
Technique

How Much HRIG to Infiltrate at Each Site

Principle: Infiltrate as much of the calculated total HRIG dose as anatomically possible into and around each bite or exposure wound to flood the area for local neutralization.

  • For multiple wounds, divide the total dose proportionally by wound size/depth and infiltrate each site.
  • If the full dose cannot be infiltrated due to limited tissue capacity, give the remainder IM at a site distant from the vaccine.
  • No fixed per-wound volume: adjust to wound anatomy and avoid excessive pressure or tissue injury.
  • If needed to increase infiltrable volume, consider dilution with an appropriate diluent (CDC allows NS; follow product label—HyperRAB uses D5W if dilution is required).
  • Use gentle pressure and a fanning technique along wound edges and tracks.
  • Prioritize hands/face/neck; for digits, use smaller aliquots in multiple passes to avoid pressure injury.
Clinical Q&A

Rabies PEP — Fast Answers for Clinicians

PEP window: Start as soon as possible; effective even after days–weeks if the patient is asymptomatic. HRIG only through Day 7 from first vaccine dose.

Delay start? Consider short delay only if a low-risk animal is available for rapid testing/10-day observation; otherwise initiate PEP and stop if negative.

Bat, no bite marks: If exposure cannot be ruled out, give full PEP; with no wound, give entire HRIG dose IM distant from vaccine.

Why vaccine + HRIG? HRIG = immediate passive antibodies at wounds; vaccine = active immunity (~7 days). Separate sites to avoid neutralization.

Dilution: Acceptable to dilute to infiltrate all wounds (CDC). HyperRAB 300 IU/mL: if dilution required, use D5W per label (not NS).

IM/site logistics: Split large volumes across multiple muscles (deltoids & thighs). Practical adult site capacities: deltoid ~0.5–2 mL; thigh ~1–5 mL.