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BCG (Bacillus Calmette-Guerin) is a vaccine against tuberculosis prepared from attentive mycobacteria that cause this disease in cattle. It is used to prevent tuberculosis in humans and has several other uses.
History of the BCG vaccine
BCG was created in France by two scientists – Albert Calmette and Camille Guerin – and put into use in 1921. Calmette and Guerin isolated a bacterial strain that causes tuberculosis in cattle and used a vaccine developed on this basis in humans. The BCG vaccine has varying efficacy. For this reason, it is used in Europe as a tuberculosis prophylaxis, but not in the USA.
How does BCG work?
The BCG vaccine, which is approved for human use, makes the body immune to tuberculosis, and when it comes into contact with mycobacteria, it turns on a program to combat these microbes, increasing the chance of the disease not developing. The very first dose of BCG protects against the most severe forms of tuberculosis and significantly reduces the risk of contracting this disease. The live strains of bacteria in the BCG vaccine are appropriately changed and weakened so that the body learns to respond properly to these pathogenic organisms without causing the vaccinated child to become ill.
When is the BCG vaccine given?
Vaccination against tuberculosis with BCG in Poland is performed 24 hours after the birth of a child or (if the child is sick or too weak) as soon as possible after discharge from the hospital. BCG vaccine is administered to children simultaneously with vaccination against hepatitis B. BCG vaccination is obligatory in Poland. They should be given up to the age of 15 at the latest. However, in some cases, such as decreased immunity, the negative consequences of giving this vaccine to a child should be considered.
- Also read: Is Tuberculosis Coming Back? Symptoms and Treatment
Possible complications after BCG vaccination
After BCG vaccination is given, a small infiltrate with vesicle may appear at the injection site. This lesion heals quickly and usually leaves no traces. Two or three weeks after vaccination, another infiltrate appears in this area and lasts for several weeks. A pustule forms on top of it, and then an ulcer appears that heals spontaneously after a few months. It leaves a characteristic scar. In some cases, after administration of BCG, lymphadenopathy may appear in the armpit on the vaccination side. This is not cause for concern; this symptom is usually self-limiting. Symptoms following the administration of the BCG vaccine that require consultation with a pediatrician include high fever, purulent discharge at the injection site, swelling or lump at the injection site, and a tumor or large swelling in the armpit on the side where the vaccination was performed. However, such complications after BCG administration are statistically rare. Basically, the use of BCG is safe.
Why is the BCG vaccine important and even necessary?
Tuberculosis is a very serious and severe disease, in many cases the patient’s death. The bacteria that cause it (mycobacteria) spread with great ease through contact with the saliva of an infected person, causing further infections. At a time when ways to protect against this disease were unknown, it decimated the population of Europe and other regions of the world. Among others, Fryderyk Chopin died of tuberculosis, and many other artists were also affected by it. It was especially dangerous for children and undernourished people living in poor conditions. Currently tuberculosis seems to be under control, but this is mainly due to the compulsory administration of the BCG vaccine in the first days of a child’s life. Treatment of tuberculosis is difficult and long-term. Immunity acquired after administration of the BCG vaccine means that even if a disease develops after exposure to Mycobacteria, it will be less severe and the chances of recovery are increased.
Other uses of BCG
BCG vaccine is also sometimes given for other diseases. Research is ongoing on its effects, for example, in the prevention of leprosy and in the treatment of diabetes. BCG has a 25% protective effect against leprosy, but is not used in the prevention of this disease due to the lack of unequivocal test results. However, it is used in the treatment of neoplastic changes, for example in the treatment of bladder cancer and colon cancer. Another use of BCG is in the treatment of type 1 diabetes. Clinical studies have shown that BCG is more than 30 percent effective in this case.