BCG Vaccine (TB vaccine)

Key vaccine facts

This vaccine gives protection against tuberculosis (TB) infection. It is 70-80% effective against the most severe forms of TB, such as TB meningitis. However, it is less effective in preventing the form of TB that affects the lungs.

The BCG vaccine contains live bacteria that have been weakened (attenuated), so that they stimulate the immune system but do not cause disease in healthy people. However the vaccine should not be given to people who are clinically immunosuppressed (either due to drug treatment or underlying illness). This is because the vaccine strain could replicate too much and cause a serious infection. This includes babies whose mothers have had immunosuppressive treatment while they were pregnant or breastfeeding. For more information see the MHRA's Drug Safety Update (April 2016).

From August 2018, the UK is using the BCG vaccine manufactured in Denmark by AJ Vaccines (see the Patient Information Leaflet). Before this, the UK was using an alternative BCG vaccine manufactured by InterVax.

Who should have the vaccine?

In the UK the BCG vaccine is not currently part of the routine childhood schedule. It is offered to those who are at higher risk of TB. The main risk groups for TB are:

Babies and children under 5 who live in an area of the UK with a high rate of TB (more than 40 cases of TB per year for every 100,000 people). In some areas of London, for example, all newborn babies are recommended to have the BCG vaccine.
Having a parent or grandparent who was born in a country where there is a high rate of TB
Living for three months or more in a country where there is a high rate of TB
Being in close contact for a prolonged period with someone who has pulmonary TB (TB affecting the lungs)

Babies and children under 16 in any of these risk groups will usually be offered the BCG vaccine. The BCG vaccine does not work well in adults, but those aged up to 35 may also be offered the vaccine if their job has a high risk of contact with people or animals infected with TB. Adults are often given a skin test before they are offered the vaccine. This is to check whether they already have antibodies to TB (see 'More information about the vaccine' towards the bottom of the page).

People with a past history of TB should not receive the vaccine. This is because they have an increased risk of adverse reactions to the vaccine.

Ingredients

The BCG vaccine used in the UK contains strains of a bacterium closely related to the one that causes TB in humans. The bacterium used for the vaccine is called Mycobacterium bovis, which causes TB in animals such as cows and badgers. The bacteria in the vaccine are weakened (attenuated) so that they do not cause disease in healthy people.

Apart from the active ingredients (the antigens), the vaccine also contains small amounts of the following ingredients:

sodium, potassium and magnesium salts
glycerol, a common non-toxic stabiliser also used in foods
citric acid

Other brands of BCG vaccine used in other countries may contain different ingredients. If you are not in the UK, ask for the Patient Information leaflet for the vaccine you are offered.

Side effects

Very common side effect (affecting 9 out of 10 people):

Hardness at the injection site, followed by a raised blister.

Uncommon side effects (affecting up to 1 in 100 people at each dose):

Headache and a raised temperature (fever)
An ulcer which develops from the blister at the injection site, two to six weeks after injection. This may be painful and take several weeks or months to heal fully.
Swelling of lymph nodes in the armpit larger than 1 cm across
An enlarged lymph node that becomes infected (lymphadenitis)

Rare side effects (affecting up to 1 in 1000 people at each dose):

More severe skin reactions. These usually heal within a few weeks.
Bone inflammation (osteitis or osteomyelitis)
An abscess at the injection site

Anaphylaxis

As with any vaccine, medicine or food, there is a very small chance of a severe allergic reaction (anaphylaxis). Anaphylaxis is different from less severe allergic reactions because it causes life-threatening breathing and/or circulation problems. It is always extremely serious but can be treated with adrenaline. Health care workers who give vaccines know how to do this. In the UK between 1997 and 2003 there were a total of 130 reports of anaphylaxis following ALL immunisations. Around 117 million doses of vaccines were given in the UK during this period. This means that the overall rate of anaphylaxis is around 1 in 900,000.

More information on side effects

Reactions listed under ‘possible side effects’ or ‘adverse events’ on vaccine product information sheets may not all be directly linked to the vaccine. See Vaccine side effects and adverse reactions for more information on why this is the case.

If you are concerned about any reactions that occur after vaccination, consult your doctor. In the UK you can report suspected vaccine side effects to the Medicines and Healthcare products Regulatory Agency (MHRA) through the Yellow Card Scheme. You can also contact the MHRA to ask for data on Yellow Card reports for individual vaccines. See more information on the Yellow Card scheme and monitoring of vaccine safety.

More information about the vaccine

The tuberculin skin test (also called the Mantoux test) may be given before you are offered the BCG vaccine. If you develop a hard red lump at the test site, this is a positive result. It means that your immune system already recognises TB, because you have been exposed to the disease in the past. In this case you should not be given the BCG vaccine because you already have some immunity to TB, and the vaccine may cause unpleasant side effects. If you have no reaction to the skin test, this is a negative result, and you can safely have the BCG vaccine.

The BCG vaccine was introduced into the UK schedule in 1953. At first it was offered to children of school leaving age (14 years old) because TB was most common in young adults at this time. Rates of TB in the UK were already falling, and they continued to fall after the vaccine was introduced. In the 1960s it was realised that there were higher numbers of TB cases in people coming to the UK from countries with high rates of TB. At this point BCG vaccination was introduced for babies born in the UK to parents from countries with high rates of TB. Vaccination of all children aged 10-14 continued until 2005, when it was decided that TB rates in the general population had fallen to such a low level that universal BCG vaccination was no longer needed. The UK programme now targets babies and children who are most at risk of exposure to TB, with the aim of preventing the more serious childhood forms of TB.

The vaccine is given just under the skin (intradermally), usually in the left upper arm. This is the recommended site, so that small scar left after vaccination can be easily found in the future as evidence of previous vaccination. No other vaccine should be given in the same limb as the BCG for three months afterwards, because of the risk of lymphadenitis (an enlarged lymph node that becomes infected).

BCG stands for ‘Bacillus Calmette-Guérin’, and is named after the two French scientists who developed the first TB vaccine – Albert Calmette and Camille Guérin.