BCG Vaccine
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BCG Vaccine

(Tuberculosis Vaccine)

En Español (Spanish Version)

What Is Tuberculosis?

Tuberculosis , or TB, is a bacterial infection caused by the Mycobacterium tuberculosis bacterium. The bacteria typically infect the lungs, but they can infect other areas of the body like the kidney, spine, or brain.

Tuberculosis is transmitted from person to person through the air. When a person coughs or sneezes, the bacteria travel into the air and may be inhaled by a person standing nearby.

The tuberculosis bacteria may be inhaled, but it may not necessarily cause infection or illness right away. The bacteria may remain dormant in the body (called latent tuberculosis), but may become active and cause symptoms at any time.

At one point, tuberculosis was the leading cause of death in the United States. As treatments for TB were developed, the incidence of TB began to drop. Today, the prevalence of the illness is much lower in the US, but it does still exist.

Tuberculosis is still a major health problem in Africa, largely because of the high incidence of AIDS and the proclivity of AIDS and HIV-infected patients toward contracting the TB infection.

Symptoms of tuberculosis depend on where the bacteria have settled and grown in the body, but they frequently infect the lungs. Symptoms of TB infection in the lungs include:

  • A cough that is persistent for three weeks or longer
  • Chest pain
  • Coughing up blood or phlegm
  • Weakness
  • Fatigue
  • Loss of appetite
  • Fever and chills
  • Night sweats

Because it is a bacterial infection, tuberculosis can be successfully treated with antibiotics. Without treatment, however, the disease is often fatal as the bacteria continue to grow and attack organs in the body.

What Is the BCG vaccine?

The Bacille Calmette-Guerin vaccine, or BCG, prevents tuberculosis.

The vaccine contains live, weakened bacteria that are similar to M. tuberculosis. The vaccine is stored in refrigerated vials. It is given as an intramuscular injection.

Who Should Get Vaccinated and When?

The following individuals should be considered for vaccination:

  • The BCG vaccine was primarily intended for use in children.
    • It is widely administered in the developing world.
    • In the developed world, it may be given under certain circumstances, such as to children who have a negative tuberculosis skin test, but are repeatedly exposed to adults who have tuberculosis and are improperly or ineffectively treated for the condition.
  • Healthcare workers, especially those who treat a large number of patients with isoniazid- and rifampin-resistant tuberculosis strains
  • People who live or work in highly populated facilities like nursing homes, hospitals, correctional facilities
  • Mycobacteriology laboratory workers
  • Healthcare workers in areas where tuberculosis cannot be properly contained

The BCG vaccine is a subcutaneous injection. It is usually only required once, but may be administered again in some settings.

What Are the Risks Associated With BCG Vaccine?

Note that the BCG vaccine may cause a tuberculosis diagnostic skin test to have a false-positive reading. This means that you may be tested positive for TB, even though you do not have the disease.

Common side effects of the vaccine include:

  • Swollen lymph nodes
  • Redness at the injection site
  • Fever
  • Bloody, frequent, or painful urination
  • Abdominal discomfort or vomiting

Symptoms of an allergic reaction, which require immediate medical attention, include severe skin rash, trouble breathing or swallowing, or wheezing.

Who Should Not Get Vaccinated?

The following individuals should not get vaccinated:

  • Individuals with compromised immune systems, such as those who are infected with HIV/AIDS
  • Individuals who may be undergoing organ transplantation
  • Pregnant women

Because TB is airborne, prevention of airborne transmission is important.

What Happens in the Event of an Outbreak?

Controlling tuberculosis consists of treatment with antibiotics and limiting an infected person's exposure to uninfected individuals. It is important to finish the entire course of antibiotics as prescribed to eliminate the bacteria and the risk of spreading it to others.


US National Institute of Allergy and Infectious Disease

US National Library of Medicine


American Lung Association website. Available at: Accessed February 6, 2007.

Division of Tuberculosis Elimination, CDC Fact Sheets website. Available at: Accessed February 6, 2007.

Questions and answers about TB. US Centers for Disease Control and Prevention website. Available at: Accessed February 6, 2007.

Last reviewed February 2008 by David Horn, MD, FACP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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