Bacillus Calmette-Guerin (BCG) Vaccine

Reviewed by: HU Medical Review Board | Last reviewed: January, 2022.

The Bacillus Calmette-Guerin (BCG) vaccine can be used in several ways. Depending on the formulation, approved uses of BCG vaccine include:

  • Preventing tuberculosis infection1
  • Treating bladder cancer2

BCG vaccine also has been used to treat stage III or recurrent melanoma for many years.3 When used for melanoma, it is injected directly into the tumor. This use of the BCG vaccine has not been approved by the US Food and Drug Administration.

How does BCG vaccine work?

The BCG vaccine is a weakened but live strain of bacteria called Mycobacterium bovis. In theory, when the bacteria are introduced to the body, they draw immune cells to fight them.4 The result is a non-specific immune response.5 This means that immune cells mount a general attack on the invading bacteria. In the process, they also destroy nearby abnormal cancer cells.4

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How effective is BCG vaccine?

Most melanoma tumors have a partial or complete response to BCG vaccine, although the response does not last.6 Studies show that BCG produces a complete response in about 90% of melanoma skin tumors and 45% of melanoma tumors under the skin.6

A few people also have a response in distant tumors.6 This suggests that treatment may train immune cells to recognize tumor antigens and fight distant tumors. However, this result is not consistently found in studies.3

What are the side effects of BCG vaccine?

The side effects of BCG vaccine can be severe. With the approval of new medications for melanoma, treatment of melanoma with BCG vaccine has become uncommon.

Side effects of the BCG vaccine include fever, chills, excessive sweating, joint pain, general discomfort or illness, and swelling of the face or throat.5 Other potentially serious risks include:1,3,5

  • Widespread BCG infection
  • Widespread clotting problems
  • Skin infection (cellulitis)
  • Skin break down (ulceration) at the injection site

Who should not take BCG vaccine?

BCG vaccine is a weakened but live bacteria. For this reason, you should not use BCG vaccine if you have a weakened immune system due to disease or medical treatment.1

BCG vaccine is not recommended during pregnancy or while breastfeeding. If you are pregnant, plan to become pregnant, or are breastfeeding or plan to breastfeed, talk with your doctor about the best options.