When should Human Tetanus Immunoglobulin (HTIG) and Human Rabies Immunoglobulin (HRIG) be administered to a patient exposed to tetanus or rabies through an animal bite or contaminated wound?

When to Administer HTIG and HRIG

Human Tetanus Immunoglobulin (HTIG) should be given for contaminated wounds in patients with incomplete tetanus vaccination (<3 doses or unknown status), while Human Rabies Immunoglobulin (HRIG) must be administered immediately at 20 IU/kg for all previously unvaccinated persons with rabies exposure, regardless of wound type. 1, 2

Human Tetanus Immunoglobulin (HTIG) Administration

Indications Based on Wound Type and Vaccination History

Clean, minor wounds:

• HTIG is not indicated regardless of vaccination history 2
• Give tetanus toxoid booster only if >10 years since last dose 2

All other wounds (contaminated with dirt, puncture wounds, traumatic wounds):

• Give HTIG if: 2
  • Unknown vaccination history, OR
  • <3 documented tetanus toxoid doses
• Do not give HTIG if: 2
  • ≥3 documented tetanus toxoid doses (give toxoid booster only if >5 years since last dose)

HTIG Dosing and Administration

• Administer at a separate site from tetanus toxoid using a separate needle and syringe 2
• Follow manufacturer's package insert for specific dosing 2
• Must be given within 6 months of potential exposure for immunocompromised patients (e.g., rituximab-treated) 3

Human Rabies Immunoglobulin (HRIG) Administration

Indications for HRIG

HRIG is required for all previously unvaccinated persons with rabies exposure, including: 1, 4

• Bite exposures (any penetration of skin by teeth)
• Non-bite exposures (scratches breaking skin, mucous membrane contamination)
• Exposures from any high-risk animal (bats, raccoons, skunks, foxes, monkeys, cats, dogs)

HRIG is NOT indicated for: 1, 3

• Previously vaccinated persons (those who completed pre-exposure or post-exposure vaccination with cell culture vaccine)
• Persons with documented rabies virus neutralizing antibody titer

Critical Timing for HRIG Administration

Administer HRIG as soon as possible, ideally within 24 hours of exposure 4

• If not given on day 0, HRIG can be administered up to and including day 7 of the vaccine series 1, 4
• Beyond day 7, HRIG is contraindicated because vaccine-induced antibody response is presumed to have occurred 1, 5
• Begin treatment regardless of time interval since exposure, as rabies incubation periods exceeding 1 year have been documented 4, 3

HRIG Dosing and Administration

Dose: 20 IU/kg (0.133 mL/kg) body weight for all ages 1, 4

Administration technique: 1, 6

1. Infiltrate the full calculated dose thoroughly around and into all wounds if anatomically feasible
2. Inject any remaining volume intramuscularly at a site distant from vaccine administration
3. Never administer in the same syringe or anatomical site as the vaccine

Common Pitfalls to Avoid

• Never exceed the recommended 20 IU/kg dose - excess HRIG can partially suppress active antibody production 1, 5
• Never give HRIG to previously vaccinated persons - it interferes with anamnestic response and is contraindicated 3, 6
• Never delay HRIG while attempting to locate or test the animal - this is a medical urgency 4
• Failure to infiltrate adequate HRIG at wound sites has been associated with rare postexposure prophylaxis failures 1

Special Populations

Immunocompromised patients (e.g., rituximab-treated): 3

• Still require HRIG at standard 20 IU/kg dose
• Use extended 5-dose vaccine schedule (days 0,3,7,14,28) instead of standard 4-dose regimen
• Consider serologic testing to confirm adequate antibody response

Previously vaccinated persons re-exposed to rabies: 3, 6

• Give only 2 vaccine doses (days 0 and 3)
• Do not give HRIG - it is contraindicated in this population

Concurrent Wound Management

For both tetanus and rabies exposures: 1

• Immediately wash wounds thoroughly with soap and water for 15 minutes
• Apply povidone-iodine solution or other virucidal agent
• Assess need for tetanus prophylaxis in all rabies exposures
• Consider antibiotic prophylaxis based on wound characteristics
• Avoid suturing when possible