Bacille Calmette-Guérin (BCG) Vaccine
The BCG vaccine is a live attenuated vaccine derived from Mycobacterium bovis, primarily used to protect against severe forms of childhood tuberculosis (TB), such as TB meningitis and miliary TB.
1. Vaccine Profile
| Parameter | Details |
|---|---|
| Type | Live attenuated (M. bovis). |
| Route | Intradermal (Left upper arm). |
| Dose | 0.05 ml (up to 1 month of age); 0.1 ml (>1 month). |
2. Clinical Considerations
- Timing: Ideally, given at birth or as early as possible.
- Local Reaction: A small papule appears, followed by an ulcer, which eventually heals into a characteristic scar. This is a normal immune response.
- Contraindications: Severe immunodeficiency (e.g., symptomatic HIV/AIDS).
NEET PG Hint: Remember, the “BCG scar” serves as proof of immunization. If a newborn is exposed to a mother with active infectious TB, the birth dose of BCG should be deferred until 6 months of chemoprophylaxis is completed. Also, BCG is not recommended for HIV-positive infants due to the risk of disseminated BCG infection.