DPT Vaccine
Overview
- Composed of diphtheria toxoid, tetanus toxoid, and killed whole-cell or acellular pertussis bacilli.
- Adsorbed on insoluble aluminum salts acting as adjuvants.
- Standard formulations include DTwP, DTaP, DT, Td, and Tdap.
Vaccine Composition
| Component | DTwP Vaccine | DTaP Vaccine | Tdap Vaccine |
|---|---|---|---|
| Diphtheria toxoid | 20-30 Lf | 20-30 Lf | 2 Lf |
| Tetanus toxoid | 5-25 Lf | 5-25 Lf | 5 Lf |
| Pertussis antigen | >4 IU (Whole-cell killed) | >4 IU (Inactivated toxin, FHA, pertactin) | Reduced acellular pertussis |
| Target age group | <7 years | <7 years | >7 years |
Administration And Storage
- Dose: 0.5 mL.
- Route: Intramuscular.
- Site: Anterolateral aspect of mid-thigh in infants; deltoid in older children.
- Storage: 2-8°C.
- Temperature sensitivity: Freeze-sensitive; discard if frozen accidentally.
Immunization Schedule
- Primary schedule: 6, 10, and 14 weeks.
- First booster: 15-18 months.
- Second booster: 4-6 years.
- Adolescent booster: Tdap at 10-12 years.
- Pregnancy: Single dose of Tdap during each pregnancy, preferably at 27-36 weeks.
- Catch-up (<7 years): DTwP or DTaP at 0, 1, and 6 months.
- Catch-up (>7 years): Tdap followed by Td at 1 and 6 months.
Efficacy And Protection
- Diphtheria and tetanus: Protective efficacy exceeds 95%.
- Pertussis: Efficacy ranges from 70-90%.
- Duration: Immunity wanes over 6-12 years, necessitating regular boosters.
- Comparison: DTwP provides superior, longer-lasting immunity compared to DTaP.
Adverse Reactions
- Minor: Local pain, swelling, redness, fever, fussiness, anorexia.
- Severe: Hypotonic-hyporesponsive episodes, inconsolable cry >3 hours, fever >40.5°C, seizures, encephalopathy.
- Incidence of adverse effects increases with subsequent doses.
Contraindications And Precautions
- Absolute contraindications: Anaphylaxis to previous dose, encephalopathy within 7 days of previous dose.
- Age limit: DTwP and DTaP strictly contraindicated beyond 7 years due to increased reactogenicity.
- Relative contraindication: Progressive neurological disease.
- Precautions: Fever >40.5°C within 48 hours, hypotonic-hyporesponsive episodes within 48 hours, persistent crying >3 hours within 48 hours, seizures within 72 hours of previous dose.
- Alternative: Administer DT or Td instead of DTP if pertussis component contraindicated.