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# BCG vaccine (bacille Calmette-Guérin)

Live attenuated tuberculosis vaccine. It protects children from severe forms, such as tuberculous meningitis and miliary tuberculosis.

Updated 2026-11-01

- Class: [Bacterial and antimalarial vaccines](https://durgical.com/en/pharmacology/classes/bacterial-and-antimalarial-vaccines/)
- Target: Cell-mediated immunity against Mycobacterium tuberculosis
- ATC code: J07AN01
- WHO Model List of Essential Medicines

Also called: Bacille Calmette-Guérin, Tuberculosis vaccine

## Mechanism of action

It contains a live attenuated strain of Mycobacterium bovis. Limited replication in the skin induces cell-mediated immunity (T cells and activated macrophages) that limits spread of tuberculosis. It prevents deaths and severe forms in childhood; its protection against adult pulmonary tuberculosis is variable.

- Live attenuated bacteria are placed in the skin
- They activate T cells and macrophages against mycobacterial antigens
- Cell-mediated immunity contains bloodstream spread
- Protects mainly against TB meningitis and miliary TB in children

## Pharmacokinetics

**Absorption**
Single intradermal dose, often near birth; the bacteria replicate to a limited extent in the skin

**Onset and duration**
Cell-mediated immunity develops over the following weeks

## Indications

- Prevention of severe tuberculosis in children in countries with a high burden of the disease [Tuberculosis →](https://durgical.com/en/conditions/tuberculosis/)

## Adverse effects

### Common

- Local inflammatory reaction at the intradermal site

### Serious (rare, important)

- Disseminated infection by the vaccine bacterium in immunosuppressed people (why it is contraindicated in them)

## Contraindications

- Immunosuppression, including HIV infection
- Pregnancy

## Key interactions

**Tuberculin skin test**
BCG can cause a false-positive tuberculin skin test; interferon-gamma release assays (IGRA) are not affected

## What is monitored

- Immune status and maternal HIV exposure before giving
- Course of the local reaction

## Administration and safety

- Strictly intradermal
- Live vaccine: keep in the cold chain as the leaflet states
- Not given to immunosuppressed people

## Nursing care

- Confirm there is no immunosuppression (including the newborn's HIV exposure)
- Record the vaccine and batch on the vaccination card
- Explain to the family why a future tuberculin skin test may be positive

## Pregnancy and breastfeeding

Contraindicated in pregnancy because it is a live vaccine.

## Memory aid

BCG = "Baby's Coverage Guarantee" against severe forms (meningitis and miliary), not against all tuberculosis.

## Test yourself

Think of the answer, then tap the question to see it.

## What does BCG protect against best?

Severe forms of tuberculosis in children, such as tuberculous meningitis and miliary tuberculosis; its pulmonary protection in adults is variable.

## Why is BCG contraindicated in people with HIV?

It is a live vaccine: in an immunosuppressed person the attenuated bacterium can disseminate.

## Which diagnostic test is preferred in a BCG-vaccinated person, and why?

IGRA (a blood test), because BCG can make the tuberculin skin test positive but does not affect IGRA.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/bcg-vaccine/)

## Related conditions

- [Tuberculosis](https://durgical.com/en/conditions/tuberculosis/)

[← Back to the class: Bacterial and antimalarial vaccines](https://durgical.com/en/pharmacology/classes/bacterial-and-antimalarial-vaccines/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Bacille Calmette-Guérin (BCG) Vaccine for Tuberculosis](https://www.cdc.gov/tb/hcp/vaccines/index.html) (Centers for Disease Control and Prevention, 2025); [Tuberculosis](https://www.who.int/news-room/fact-sheets/detail/tuberculosis) (World Health Organization, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 40 (McGraw Hill, 2023); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=J07AN01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/bcg-vaccine/