BCG
Core Characteristics
| Feature | Detail |
|---|---|
| Vaccine Strain | Live attenuated Mycobacterium bovis Calmette-GuΓ©rin strain. |
| Indian Strain | Copenhagen (Danish 1331) strain produced at Guindy, Tamil Nadu. |
| Presentation | Lyophilized powder in vacuum-sealed dark multidose vials. |
| Antigenic Content | Contains 0.1-0.4 million live viable bacilli per 0.1 mL dose. |
| Diluent | Requires reconstitution with sterile normal saline. |
| Storage | Store at 2-8Β°C. Highly sensitive to heat and light. |
| Post-Reconstitution | Discard within 4-6 hours to prevent bacterial contamination and toxic shock syndrome. |
Dosage And Administration
| Parameter | Specification |
|---|---|
| Dose | 0.05 mL for infants under one month. 0.1 mL for infants over one month. |
| Route | Intradermal injection raising a 5-7 mm wheal. |
| Site | Left upper arm at insertion of deltoid muscle. |
| Schedule | Administer at birth or as early as possible. |
| Maximum Age | Up to 1 year in National Program, catch-up permitted till 5 years by IAP. |
Immunogenicity And Efficacy
- Primarily induces cell-mediated immunity.
- Protective efficacy against primary pulmonary infection remains low (8-79%).
- Affords excellent protection (72-100%) against severe disseminated forms like miliary tuberculosis and tubercular meningitis.
- Immunity duration typically wanes over 10-15 years.
- Scar failure occurs in approximately 10% of recipients but does not signify immunization failure due to positive in vitro responses,.
- Exhibits non-specific heterologous protection against neonatal sepsis and respiratory viral infections.
Normal Vaccine Reaction
- Papule formation measuring 4-8 mm begins around 2-3 weeks post-vaccination.
- Lesion ulcerates by 3-6 weeks.
- Heals with permanent scar formation by 6-12 weeks.
Adverse Events
- Local complications include persistent ulceration and ipsilateral regional (axillary or cervical) lymphadenitis.
- Suppurative lymphadenitis requires needle aspiration; surgical excision reserved for failed repeated aspirations.
- Severe rare complications involve osteitis, osteomyelitis, and disseminated BCG infection.
- Disseminated BCG disease incidence measures two cases per one million vaccinations.
Contraindications And Special Populations
- Contraindicated in severe congenital and acquired immunodeficiency syndromes, including symptomatic HIV.
- Contraindicated during immunosuppressive therapy or malignancies involving bone marrow.
- Asymptomatic HIV-exposed neonates must receive vaccination at birth.
- Safe and effective for administration in medically stable preterm and low birth weight infants at discharge.