BCG Vaccine (TB vaccine)

Vaccine

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This vaccine gives protection against tuberculosis (TB) infection, a disease spread person to person through the air.  

In the UK the BCG vaccine is not currently part of the routine childhood schedule, although it is offered to people who are at higher risk of contracting TB (see Who should get this vaccine).

The vaccine is given just under the skin (intradermally), usually in the left upper arm. This is the recommended site, so that the small scar left after vaccination can be easily found in the future as evidence of previous vaccination.

Although often thought of as a lung disease, TB can infect other parts of the body, including the brain. The vaccine 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.

 

In the UK the BCG vaccine is not currently part of the routine childhood schedule because rates of TB among the general population are very low. It is offered to those who are at higher risk. 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 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 TB in their lungs (pulmonary TB)
  • healthcare workers or lab workers who have either direct contact with TB patients or with potentially infectious clinical materials
  • veterinary and staff who handle animals or animal materials, which could be infected with TB 

Babies and children under 16 in any of these risk groups will usually be offered the BCG vaccine. From 1 September 2021, eligible babies born on or after this date should be offered the BCG vaccine by 28 days or soon after (see more information about this vaccine).

The addition of screening for Severe Combined Immunodeficiency (SCID) to the routine newborn screening test at five days of age, in six areas across England, resulted in a change to when the BCG vaccine is delivered for all babies in England. SCID screening is used to identify babies with a rare genetic condition that affects the immune system and could pose a risk to them if they receive live vaccines, such as BCG. The BCG vaccination is now given when the SCID screening outcome is available, which is approximately 14 to 17 days after birth, so that those with this rare condition can be identified and treated early. See “more information about the vaccine” below.

The BCG vaccine does not work well in adults, although adults aged 35 or under 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 to check whether they already have immune responses to TB. If they already have immune responses, they should not have the vaccine. 

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 about these groups who should not have a BCG, see the MHRA's Drug Safety Update (April 2016).

 

 

All vaccines go through rigorous testing and regulatory processes that can take up to 15 years to ensure they are safe and effective. Like all medicines, vaccines can cause side effects, but not everyone experiences them.

The BCG vaccine contains live bacteria that have been weakened (attenuated), so they stimulate the immune system but do not cause disease in healthy people. 

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

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.

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.

 

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:

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.

 

Tuberculin skin test

Some people need to have the tuberculin skin test (also called the Mantoux test) before they are offered the BCG vaccine. This is to check whether they need a BCG or not. If they develop a hard red lump at the test site, this is a positive result. It means that their immune system already recognises TB, because of previous exposure to TB. In this case, a person should not be given the BCG vaccine because they 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.

History of the 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.

Before 2022, the BCG vaccine was given to eligible babies soon after birth, often whilst still in hospital. However, the addition of screening for Severe Combined Immunodeficiency (SCID) to the routine newborn screening test at five days of age, in six areas across England, resulted in a change. SCID screening has made it necessary to move the BCG vaccination to when the SCID screening outcome is available, which is approximately 14 to 17 days after birth. The vaccine has been moved for babies nationally, not just in the six areas where SCID screening has been introduced. This is to ensure consistency and safety for all babies across the country.

This is to ensure that babies with SCID are not given the live attenuated BCG vaccine, which could result in severe side-effects as all live vaccines are not advised (contraindicated) in babies with a SCID diagnosis.

The BCG 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, where 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.

 

Page last updated Wednesday, January 19, 2022