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.