Conditions & Treatments

Bacille Calmette-Guérin (BCG) - What it is

BCG, or Bacille Calmette-Guérin, is a vaccine given to prevent tuberculosis (TB), especially in infants and children. It reduces the risk of developing all forms of TB by 50% and deadly forms of TB by up to 80%. The risk of long-term disability and death is high in children who are infected with TB.

BCG is given to all children around the world where TB is common. Although there has been a large reduction in TB rates in Singapore since the 1950s, it is still common. Globally, a third of the world’s population is estimated to be infected with TB.

The BCG vaccine contains a weakened form of live bacteria related to TB. The administration of the vaccine makes the body’s immune system produce antibodies to fight TB. The administration is in levels that do not cause the disease.

Bacille Calmette-Guérin (BCG) - Other Information

What must I take note of?

In rare circumstances, however, BCG vaccination can lead to complications. In approximately one in 1,000 babies, it leads to the development of either:

a persistent abscess or pus collection over the BCG site beyond the 12th week, or
an enlarged lymph node (which feels like a small fleshy lump) in the armpit (if the BCG vaccination was at the arm) or groin (if the vaccination was at the buttocks) that may become pus-filled or even discharge pus.

If the above occurs, you should take the baby to a doctor for further medical advice. The most severe form is widespread or “disseminated” BCG which occurs in around one out of 100,000 children who have an underlying defect in their immune systems (the body’s defence against infections). These children often have an ulcer that does not heal and/or lymph node enlargement together with enlargement of the liver and spleen. These children should be brought to specialist centres such as KK Women’s and Children’s Hospital (KKH), for further medical care.

BCG vaccination has more benefits than risks. Besides protecting your child with BCG vaccination, adults should also take precaution against TB with routine care. We hope that TB in Singapore will become less common in future so that it may not be needed anymore.