BCG immunisation

How does BCG immunisation work?

The bacillus Calmette-Guérin immunisation (also known as the BCG) contains a small number of tuberculosis (TB) germs (bacteria). When injected, the immunisation encourages your immune system to defend your body against TB infection.

See separate leaflet called Tuberculosis for more details.

BCG immunisation is also used as part of the treatment for some people who have bladder cancer.

See separate leaflet called Bladder Cancer for more details.

BCG immunisation is thought to give good protection against TB for children. It is much less effective for adults. Importantly, BCG immunisation is very good at protecting against the most severe forms of TB, such as TB meningitis in children. Although it is a good immunisation, it does not guarantee protection against TB.

Protection against TB has been shown to last for 10-15 years after BCG immunisation when given to children. There is no evidence that repeat vaccination offers any further protection. BCG immunisation seems to be much less effective when it is given to adults.

Previously, all schoolchildren in the UK were routinely given BCG immunisation at the age of 13 years. The policy changed in 2005. Rates of TB are now very low in many parts of the country. Children living in these areas have a very low risk of infection. However, in other areas, rates of TB are increasing.

Since 2005, BCG immunisation has been given to those people most at risk of TB infection. BCG immunisation should be given to:

Children

• All infants (aged 0-12 months) living in areas of the UK where there are high numbers of people with TB. This usually means some parts of big cities.

• All infants (aged 0-12 months) with a parent or grandparent who was born in a country where there is a high rate of TB infection - for example, Pakistan, Africa and Eastern Europe.

• Children aged 1-15 years who have not already been vaccinated and have a parent or grandparent who was born in a country where there is a high rate of TB infection.

• Previously unvaccinated children under 16 years of age who are contacts of cases of respiratory TB.

• Previously unvaccinated children under 16 years of age:

  • Who were born in a country with a high rate of TB infection; and

  • Who are Mantoux or interferon-gamma release assay (IGRA) negative.

  • Who come from a high-incidence country.

See separate leaflet called Tuberculosis for further information on the Mantoux skin test and the IGRA test.

Adults

People between the ages of 16-35 years who are in contact with people who have active pulmonary or laryngeal TB should be immunised if they are Mantoux or IGRA negative.

People in the following jobs are more likely to come into contact with someone with TB:

• Healthcare workers who have contact with patients with TB or with some test samples from these patients - for example, blood or phlegm (sputum) tests.

• Laboratory staff who have contact with patients with TB or with some test samples from these patients - for example, blood or sputum tests.

• Veterinary staff and staff such as abattoir workers who handle animal species known to sometimes have TB infection.

• Prison staff working directly with prisoners.

• Staff of care homes for the elderly.

• Staff of hostels for homeless people and centres for refugees and asylum seekers.

People in these jobs who have not been vaccinated and have a negative Mantoux or IGRA test are recommended to receive BCG immunisation, irrespective of age.

People aged 16-35 years from sub-Saharan Africa or from countries where 500 or more cases of TB occur in every 100,000 people should also be immunised.

BCG immunisation may be needed for people who have not had a BCG jab and have a negative Mantoux test, depending on where they are going. BCG immunisation is recommended for those aged under 35 years who are going to live or work with local people for more than three months in a country where there is a high rate of TB infection.

The Government's advice about who should have BCG immunisation varies from time to time. The latest information can be found on the Health Security Agency website (see under 'Further reading & references' at the end of the leaflet online).

It works better in children aged under 16 years than in adults, but it's still worth adults at high risk having it.

It's good at protecting from the real problem cases like TB meningitis in children, although it doesn't offer guaranteed protection.

One shot is all it takes; there's no point in having another one.

The BCG jab is given as a single injection into the skin of the outside of the upper arm, usually the left arm.

For at least three months following BCG immunisation, no other immunisation should be injected into the arm which received the BCG jab.

The BCG immunisation should not be given to:

• Those who have already had a BCG immunisation.

• Those with a past history of tuberculosis (TB) infection.

• Those with a strong reaction to Mantoux skin testing.

• Those who have had a confirmed severe allergic reaction to any substance in the BCG immunisation.

• Newborn babies who live in a house where someone has definite or suspected TB infection.

• People who have reduced body defences (immune system) - for example, those using steroid tablets, those with AIDS or those who have cancer.

BCG immunisation can be given if you have a minor illness without a high temperature (fever) and are not feeling unwell. If you feel very unwell, the BCG jab should be delayed until you have recovered. BCG immunisation can be given during pregnancy and when breast-feeding. However, it is usually delayed during pregnancy, especially during early pregnancy.

BCG immunisation is very safe. Occasionally reactions can occur at the injection site - for example, infection and scarring. Allergy reactions can occur but are also uncommon.

Other uncommon side-effects can include headache, swelling of lymph glands in the armpit and an ulcer at the site of the injection.

It is possible for BCG immunisation to cause a TB infection in the body but this is very rare.