What is the recommended DT (diphtheria and tetanus) vaccine protocol for contacts of a diphtheria case?

DT Vaccine Protocol for Contacts of Diphtheria Cases

For close contacts of diphtheria cases, vaccination with diphtheria toxoid-containing vaccine is recommended based on vaccination history: unvaccinated or partially vaccinated contacts should receive an immediate dose and complete the primary series, while fully vaccinated contacts who haven't received a booster in the past 5 years should receive a booster dose. 1

Identification of Close Contacts

Close contacts who require management include:

• Household members
• Persons with habitual, close contact with the patient
• Individuals directly exposed to oral secretions of the patient 2

Comprehensive Management Protocol

Step 1: Culture and Antimicrobial Prophylaxis

• Obtain throat cultures from all close contacts before starting antimicrobial prophylaxis
• Administer antimicrobial prophylaxis immediately without waiting for culture results 1
• Options for prophylaxis:
  • Benzathine penicillin (single IM injection):
    • 600,000 units for persons <6 years old
    • 1,200,000 units for persons ≥6 years old
  • OR oral erythromycin: 7-10 day course
    • Children: 40 mg/kg/day
    • Adults: 1 g/day 2

Step 2: Vaccination Assessment and Management

Vaccination protocol depends on previous immunization status:

1. For contacts with unknown vaccination status or <3 doses of diphtheria toxoid:

   • Administer immediate dose of age-appropriate diphtheria toxoid-containing vaccine
   • Complete primary vaccination series according to schedule 1

2. For fully vaccinated contacts (≥3 doses) who haven't received a booster in past 5 years:

   • Administer age-appropriate booster dose of diphtheria toxoid-containing vaccine 1

3. For fully vaccinated contacts with booster within past 5 years:

   • No additional doses needed

Step 3: Monitoring and Follow-up

• Monitor all close contacts daily for 7 days for signs of disease
• Perform follow-up cultures after completion of antimicrobial therapy
• For persistent carriers, administer additional 10-day course of oral erythromycin 1

Special Considerations

• Pregnancy: While no evidence exists that tetanus and diphtheria toxoids are teratogenic, waiting until the second trimester to administer Td is a reasonable precaution 2

• Previous adverse reactions: Persons who experienced Arthus-type hypersensitivity reactions or temperature >103°F (39.4°C) following prior tetanus toxoid should not receive Td more frequently than every 10 years 2

• Contraindications: If contraindications to tetanus toxoid-containing preparations exist for someone who has not completed primary immunization and has a wound that is neither clean nor minor, only passive immunization should be given using tetanus immune globulin (TIG) 2

Common Pitfalls to Avoid

• Delaying antimicrobial prophylaxis while waiting for culture results
• Incomplete contact tracing
• Overlooking vaccination status assessment
• Inadequate follow-up of contacts
• Failing to perform post-treatment cultures 1

By following this protocol, healthcare providers can effectively prevent secondary transmission of diphtheria and reduce morbidity and mortality associated with this potentially fatal disease.