What is the BCG vaccine used for?
- Preventing tuberculosis.
This vaccine is no longer given to all children as part of the schools vaccination programme. Instead there is now an improved programme of targeted vaccination for those individuals who are at greatest risk of contracting the disease. The main risk groups include: babies born into families with a history of TB in the last five years; infants under one year of age born in areas where the incidence of TB is 40 cases per 100,000 people or higher; babies and children under 16 years of age whose parents or grandparents were born in a country with an incidence of TB of 40 cases per 100,000 people or higher, new immigrants from countries with a high incidence of TB who have not already been vaccinated and children who have come into close contact with somebody infected with respiratory TB.
Children who would previously have been vaccinated through the schools programme will now be screened for risk factors for TB and only given the vaccine if they are at risk. Other high risk groups who are recommended vaccination are: contacts of people carrying tuberculosis; healthcare workers; veterinary and other workers who handle animals susceptible to tuberculosis; staff working in prisons, in residential homes and in hostels for refugees and the homeless; and children under 16 years of age intending to stay for more than three months with local people in countries with a high incidence of tuberculosis.
How does the BCG vaccine work?
The BCG vaccine contains a live but weakened form of a type of bacteria called Mycobacterium bovis. The vaccine is known as BCG because a strain of the bacterium known as Bacillus Calmette-Guerin is used. The vaccine is used to prevent tuberculosis, and works by stimulating the body's immune response to the bacteria, without actually causing the disease.
When the body is exposed to foreign organisms, such as bacteria and viruses, the immune system produces antibodies against them. Antibodies help the body recognise and kill the foreign organisms. The antibodies remain in the body to help protect the body against future infections with the same organism. This is known as active immunity.
The immune system produces different antibodies for each foreign organism it encounters. This establishes a pool of antibodies that helps protect the body from various different diseases.
Vaccines contain extracts or inactivated forms of bacteria or viruses that cause disease. These altered forms of the organisms stimulate the immune system to produce antibodies against them, but don't actually cause disease themselves. The antibodies produced remain in the body so that if the organism is encountered naturally, the immune system can recognise it and attack it. This prevents it from causing disease.
Each bacteria or virus stimulates the immune system to produce a specific type of antibody, and this means that different vaccines are needed to prevent different diseases.
The BCG vaccine stimulates the immune system to produce antibodies against Mycobacterium tuberculosis bacteria. This provides immunity against tuberculosis.
How is the BCG vaccine given?
- Before the vaccine is given you will need to have a skin test to check that you don't already have antibodies to the tuberculosis bacteria, either from a previous vaccination or from previous exposure to the disease. This test uses tuberculin PPD and is called the Mantoux test. For more information see the tuberculin PPD factsheet.
- Children up to six years of age do not need to have the Mantoux test before the vaccine is given, providing that the child has not lived or stayed for more than three months in a country with an annual TB incidence greater than 40 per 100,000 people, they have not had contact with a person with known tuberculosis and there has been no family history of tuberculosis in the last five years. All other people should have the Mantoux test before vaccination.
- The BCG vaccine is given as one dose by injection into the skin of the upper arm. The length of time that the immunity lasts is not known, but revaccination is not recommended.
Important information about the BCG vaccine
- The BCG vaccine usually causes a hardened lesion that may ulcerate and occasionally discharge. It heals over several weeks or months leaving a small flat scar. You should keep the area dry to allow it to heal, but it is not necessary to protect it from water during washing or bathing. Avoid covering it with waterproof (airtight) dressings or tight clothing, unless for short periods such as during swimming. If the ulcer starts to ooze you can cover it with a dry dressing until a scab forms, but you should still allow the air to get to it. Airtight dressings may delay the healing of the ulcer and cause a larger scar. If you get a more severe reaction or the ulcer persists seek medical advice from your doctor.
BCG vaccine should be used with caution in
- People with eczema (skin at injection site should be free from eczema).
BCG vaccine should not to be given to
- People who have ever had tuberculosis.
- People with positive skin reaction to tuberculin (Mantoux test).
- New-born babies in a household where an active TB case is suspected or confirmed.
- People who are taking anti-tuberculosis medicines.
- People with a fever (high temperature). The vaccine should be delayed until after recovery.
- People with generalised infected skin conditions.
- People with HIV infection.
- Infants born to HIV positive mothers.
- People with malignant conditions such as leukaemia and lymphoma.
- People who are having or who have recently received treatment that suppresses the activity of the immune system, for example long-term oral corticosteroids, chemotherapy, radiotherapy, medicines to prevent transplant rejection, or other immunosuppressants.
- People with decreased defences against disease or infection (impaired immune response) due to disease or treatment.
This vaccine should not be given if you are allergic to any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
If you feel you have experienced an allergic reaction after having this vaccine you should inform your doctor, nurse or pharmacist immediately.
Pregnancy and breastfeeding
Certain vaccines should not be used during pregnancy or breastfeeding. However, other vaccines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before having any vaccine.
- This vaccine is not usually given during pregnancy or breastfeeding, unless a high risk of tuberculosis infection outweighs any potential risks associated with the vaccine. Seek further medical advice from your doctor.
Possible side effects of the BCG vaccine
Vaccines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this vaccine. Just because a side effect is stated here, it does not mean that all people having this vaccine will experience that or any side effect.
Uncommon (affect between 1 in 100 and 1 in 1000 people)
- Fever (high temperature).
- Redness and tenderness at site of injection.
- Swelling of the lymph nodes near the injection site.
- Hardening of skin at injection site, followed by a lesion that may ulcerate and discharge. This will usually heal over some months, leaving a small flat scar. See the important information section above.
Rare (affect between 1 in 1000 and 1 in 10,000 people)
- Allergic reaction.
- Formation of an abscess at the injection site.
- Complications such as bone inflammation (osteitis or osteomyelitis).
The side effects listed above may not include all of the side effects reported by the vaccine's manufacturer.
If you think you have experienced a side effect from this vaccine you should check the patient information leaflet. This lists the known side effects and what to do if you get them. You can also get advice from your doctor, nurse or pharmacist. If they think it's necessary they'll report it for you.
You can also report side effects yourself using the yellow card website: www.mhra.gov.uk/yellowcard.
How can the BCG vaccine affect other medicines?
This vaccine is not known to affect other medicines.
However, people taking medicines that suppress the activity of the immune system, for example chemotherapy, high-dose corticosteroids, or immunosuppressants used following an organ transplant, may not produce adequate numbers of antibodies in response to this vaccine. As a result, the vaccine may be less effective in these people. If you are taking any of these medicines you should discuss this with your doctor.
This vaccine may be given at the same time as other vaccines, but if so, the vaccines should be given into different limbs. No other vaccines should be given into the arm used for the BCG vaccine for three months after having the BCG.
If you need to have another live vaccine after you have been given the BCG vaccine, this should not be given for at least four weeks after the BCG vaccine.
For background information about our medicine factsheets, including the references used to produce them, click here.
Last updated 24.12.2020