BCG (tuberculosis) vaccination

Page last reviewed: 13/07/2011

The Bacillus Calmette-Guérin (BCG) vaccine provides protection against tuberculosis (TB).

TB is an infection caused by a bacterium called mycobacterium tuberculosis.

The most common form of TB in Ireland affects the lungs, but it can affect other parts of the body such as the bones, joints and kidneys. It can also cause meningitis.

TB can be a very serious disease, but with effective treatment, it is possible to make a full recovery from most forms of TB.

For more information, see the Health A-Z topic about TB.

Who should have the vaccine?

The National Immunisation Advisory Committee (NIAC) is an independent expert group on immunisation. NIAC and the Health Information and Quality Authority (HIQA) have both recommended that the BCG vaccine does not now need to given routinely to all children in Ireland.

The Department of Health will make a decision on NIAC and HIQA recommendations.

The HSE must await instruction from the Department of Health regarding BCG vaccination.

BCG vaccinations may also be recommended for people who have an increased risk of developing TB, such as:

  • health workers
  • people who have recently arrived from countries with high levels of TB
  • people who have come into close contact with somebody infected with respiratory TB

About the vaccine

The BCG vaccine is made from a weakened form of a bacterium closely related to human TB. Because the bacterium is weak, the vaccine does not cause any disease but it still makes the immune system produce antibodies, which makes people who receive it immune to TB.

The BCG vaccine does not contain mercury.

The vaccine is 70-80% effective against the most severe forms of TB, such as TB meningitis in children. It is less effective in preventing respiratory disease, which is the more common form in adults.

Page last reviewed: 13/07/2011

The National Immunisation Advisory Committee (NIAC) is an independent expert group on immunisation. NIAC and the Health Information and Quality Authority (HIQA) and NIAC have both recommended that the BCG vaccine does not now need to given routinely to all children in Ireland.

The Department of Health will make a decision on NIAC and HIQA recommendations.

The HSE must await instruction from the Department of Health regarding BCG vaccination.

Mantoux (tuberculin) test

The BCG vaccine can be given to older children and adults following a Mantoux test.

A tuberculin skin test, or Mantoux test, should be carried out before the BCG vaccination is given for:

  • all individuals aged six years or over
  • infants and children under six years of age with a history of residence or prolonged stay (more than three months) in a country with an annual TB incidence of 40 per 100,000 or greater
  • those who have had close contact with a person with known TB
  • when there is a history of TB in a household contact in the last five years.

The Mantoux test checks whether you have a TB infection or disease. This is necessary as many people can become infected with the bacteria that cause TB but do not develop any symptoms (known as latent TB).

The test involves injecting your skin with a substance called purified protein derivative (PPD) tuberculin. If you have immunity to TB, your skin will be sensitive to PPD tuberculin and a hard red bump will develop at the site of the injection, usually within 48 to 72 hours of having the test.

If you develop this reaction (a positive test result), you should not be vaccinated, as the BCG vaccine has no clinical benefit and may cause unpleasant side effects.

If the test proves negative, the BCG vaccine is given.

Who should have the BCG vaccination?

There is little evidence that the BCG vaccine is effective in older people. TB vaccinations are not usually offered to people over the age of 16 unless the risk of exposure is great (for example, if they have come from Sub-Saharan Africa).


BCG vaccination is offered at birth to babies in Ireland as part of the childhood immunisation programme.

Older children and adults

  • Unvaccinated children under 16 years of age should be vaccinated.
  • Anyone 35 years and under who has come from an area where TB is widespread should be vaccinated.  (see More information, below).
  • Anyone 35 years and under who has been in close contact with someone who has pulmonary TB (TB infection of the lung) should be vaccinated.

At-risk occupations

A BCG vaccination is recommended if you are under 35 and work in an occupation with an increased risk of exposure to TB. These people include:

  • laboratory staff who are in contact with clinical materials, such as blood, urine and tissue samples
  • veterinary staff and other animal workers, such as abattoir workers, who work with animals that are susceptible to TB, such as cattle or monkeys
  • prison staff who work directly with prisoners
  • staff of care homes for the elderly
  • staff of hostels for homeless people
  • staff who work in facilities for refugees and asylum seekers

BCG vaccination is recommended for all healthcare workers who are previously unvaccinated and who have contact with patients or clinical materials irrespective of age.

Who should not have the BCG vaccination?

The BCG vaccine is not recommended for:

  • people who have already had a BCG vaccination
  • people with a past history of TB
  • people with a positive skin test
  • people who have had a previous anaphylactic reaction (severe allergic reaction) to any of the substances used in the vaccine
  • newborn babies in a household where a case of TB is suspected or confirmed
  • those who are pregnant
  • babies born to mothers who received high doses immunosuppressive drugs or who are HIV positive
  • people who have a septic skin condition
  • people who have received another live vaccine less than three weeks earlier
  • people with a weakened immune system, either as a result of a health condition (such as HIV) or treatments such as chemotherapy or immunosuppressant medication (medication that suppresses the immune system)
  • people who have cancer of the white blood cells, bone marrow or lymph nodes, such as leukaemia or lymphoma
  • people who are seriously unwell (vaccination should be delayed until they recover)

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Page last reviewed: 13/07/2011

Around 90-95% of people will develop a raised blister at the site of the injection immediately after the vaccination. This is normal, and nothing to worry about.

Two to six weeks after the injection, a small spot may appear at the site of the injection. This can be painful for a few days, but should settle. The spot will eventually heal, but it may leave a small scar.

A small number of people will get swollen glands under their arm. A small number of people will have a more severe reaction, such as deep ulcers or abscesses forming. If this happens contact your doctor or public health nurs e.

Serious side effects, such as an anaphylactic reaction (a serious allergic reaction), are very rare. They occur in less than one in a million cases.

Page last reviewed: 13/07/2011

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 have been altered so that they do not cause a TB infection but make your immune system produce antibodies. These make you immune (resistant) to the disease.

Why is TB still a problem?

It was hoped that with the invention of the BCG vaccine, and associated medications to treat TB, it would be possible to wipe out TB in the same way as smallpox.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. This has been because individuals have not completed the course of treatment or have been prescribed inappropriate treatment, or because the supply of drugs is inadequate.The BCG vaccination is effective against some severe forms of the disease, such as TB meningitis in children, but it is not 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, which makes them more likely to develop a TB infection.TB remains a global health problem and was declared a global health emergency by the World Health Organization in 1993. The rapid growth and affordability of international travel has allowed people to travel widely and this has contributed to the spread of the disease. 

How common is TB in Ireland?

In 1952, there were nearly 7,000 cases of TB notified in Ireland. The combination of better living conditions, antibiotics against TB, and BCG vaccine have dramatically reduced the number of cases of TB in Ireland. In 2008, the total number of cases notified nationally was 470. Detailed reports on the epidemiology of TB can be found here.

The people most likely to catch TB are the very young, the elderly and those with an immune system weakened either by illness or by certain medications.

More information on BCG vaccination is available in the BCG and vaccination sections of the HPSC website.

Where in the world is TB widespread?

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. If you are planning to visit a high-risk country and work or live with local people for more than a month, the BCG vaccination is usually recommended.

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 the 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.

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 you should talk to the HSE doctor 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.

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

A raised blister will appear in most people (90-95%) who are vaccinated with BCG, but not all. If your child did not have this reaction to the vaccine, it does not mean that they have not responded to it. Vaccinating individuals with BCG a second time is not recommended.

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Content provided by NHS Choices and adapted for Ireland by the Health A-Z.

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