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What is the BCG vaccine?
Bacille Calmette-Guerin or BCG is a vaccine for TB given in many countries where tuberculosis is prevalent. Tuberculosis or TB is caused by the bacterium, Mycobacterium. TB is contagious and can spread through coughing, sneezing and even talking. Contrary to popular belief, tuberculosis can infect every organ of the body, and not just the lungs. Most of the time symptoms do not manifest in infected persons and many people become infected without knowing and this is known as latent infection. But about 10% of these cases will reactivate and they will go on to develop the disease in their lifetime and become infectious to others. In countries where the vaccine is given, the dose is usually at birth in the hospital itself.
There is no follow-up vaccine and at present, no effective vaccine is available for adults. The available vaccine is able to provide 80% protection against infections e.g. brain infection but overall protection is only about 50%. The vaccine is not particularly effective in the prevention of lung infection in teenagers and adults. In young children however the vaccine is able to provide protection against the severe forms of tuberculosis known as TB meningitis (involving the lining of the brain) and miliary TB (involving the whole lung). In some countries such as the United States, this vaccination is not routinely given due to the lower risk of infection there. The vaccine is safe; a small percentage of children may develop a painful swelling of the glands under the arm that was injected, which can last for about 3 months. A slight swelling may appear one - three weeks after the shot which may later discharge. Do not use any ointment and allow the scab to heal on its own.
Dose: Vaccines available are Mycobax and TICE BCG. Shot is to be given at birth and if there is a delay, preferably before the child turns five. In older babies a test is performed and if the results show positive MT (i.e. the child is sensitized), then BCG will not be given. It is important to note that childhood TB differs from the adult form - as mentioned BCG does not protect adults from TB. In some countries booster doses are given.