Vaccinations
NHS Choices

BCG (TB) vaccine FAQs

How does the vaccine work?

Why is TB still a problem?

Where in the world is TB widespread?

Is TB contagious?

How do I know if my baby needs the BCG vaccination?

I have an allergy. Could anything in the BCG vaccine trigger that allergy?

Does the BCG vaccine contain any blood products or materials of animal origin?

I live with somebody who has a weakened immune system. If I have the vaccine, is there a risk that the bacteria in the vaccine could infect them?

Why do we no longer vaccinate teenagers with the BCG at school? How can I get my child vaccinated?

There was no scar or blister after my child's BCG jab. Did it work?

How does the vaccine work?

The BCG vaccine contains a strain of mycobacterium bovis, which is a bacterium that causes tuberculosis (TB) in cattle. The bacteria are altered so that they do not cause a TB infection, but stimulate your immune system to make you resistant to the disease.

Why is TB still a problem?

It was hoped that with the invention of the BCG vaccine and medicines, it would be possible to wipe out TB in the same way smallpox was eradicated. This has turned out to be difficult for a number of reasons.

  • Much of the initial improvement in TB in more developed countries was related to improvements in housing, nutrition and access to treatment. Poor conditions are still present in many less developed countries.
  • Several strains of TB bacteria have developed a resistance to one or more anti-TB medications, making them much harder to treat.
  • The BCG vaccination is effective against severe forms of the disease, such as TB meningitis in children, but it is not as effective against all forms of TB.
  • The global epidemic of HIV that began in the 1980s has led to a corresponding epidemic of TB cases. This is because HIV weakens a person's immune system, making them more likely to develop a TB infection.
  • The rapid growth of international travel has allowed people to travel widely and this has helped to spread of the disease.

Where in the world is TB widespread?

TB is found throughout the world. Parts of the world known to have high rates of TB include sub-Saharan Africa (all the countries south of the Sahara desert) and Asia.

For more information, see the WHO website.

Is TB contagious?

Yes. TB is spread when a person with an active infection of TB in their lungs coughs or sneezes and somebody else inhales a droplet of contaminated saliva.

However, TB is not as infectious as the common cold or flu. You usually need to spend a long time in close contact with an infected person before you catch TB. For example, infections usually spread between family members who are living in the same house.

Read more about how you catch TB.

How do I know if my baby needs the BCG vaccination?

Your midwife, practice nurse or GP will be able to tell you if a BCG vaccination is recommended for your baby.

I have an allergy. Could anything in the BCG vaccine trigger that allergy?

No. The BCG vaccine can be used safely by:

  • people who are allergic to latex (a type of rubber)
  • people who are allergic to penicillin
  • people who are allergic to dairy products, eggs and/or nuts

However, if you have any concerns, talk to your GP before going ahead with vaccination.

Does the BCG vaccine contain any blood products or materials of animal origin?

No. There are no blood products in the vaccine. All of the raw materials used to make the vaccine are from non-animal origins.

I live with somebody who has a weakened immune system. If I have the vaccine, is there a risk that the bacteria in the vaccine could infect them?

No. While the BCG vaccine is not recommended for people with a weakened immune system, they cannot catch TB from someone who has been vaccinated.

Why do we no longer vaccinate teenagers with the BCG at school? How can I get my child vaccinated?

TB is a difficult disease to catch because it requires prolonged exposure to an infected person. For example, you are very unlikely to catch it by sitting or standing next to someone who is infected. Also, rates of TB in the UK population have fallen to very low levels over the past 15 years.

The BCG vaccination programme was changed to reflect this and is now only given to people in at-risk groups.

 If your child does not come into one of the higher-risk groups, the current advice is not to give them the BCG vaccination on the NHS. There are private clinics that parents can approach for a BCG vaccination, but the NHS does not keep a list of these clinics.

Read more about who should have the BCG vaccine.

There was no scar or blister after my child's BCG jab. Did it work?

A raised blister will appear in most people vaccinated with BCG, but not everyone. If your child did not have this reaction to the vaccine, it does not mean that they have not responded to it. There's no need to vaccinate with BCG a second time.


Last Updated: 01/04/2017 09:00:00