BCG and Subsequent Tuberculosis Testing

What is BCG vaccine?
BCG stands for Bacille Calmette-Guerin vaccine.  This is a live-virus vaccine that is recommended by the World Health Organization (WHO) for use in countries where tuberculosis (TB) is a serious threat.  BCG vaccine is recommended to be given shortly after birth in order to prevent complications of tuberculosis infection.  It does NOT prevent getting TB disease in the lungs.  It prevents babies and young children from having TB spread from lungs to the central nervous system or other parts of the body.  BCG helps to prevent TB meningitis, a serious and sometimes fatal threat to babies and young children. 

What countries are using BCG vaccine?
BCG is generally not used in the United States or Western European countries.  However, it is widely used in Eastern Europe (e.g. Russia, Ukraine, Kazakhstan), Central and South American (e.g., Guatemala, Peru and Columbia), African nations (e.g., Ethiopia, Liberia), China, India, Philippines and Vietnam.

What does a BCG vaccine look like?
A brand new BCG vaccination will often be located on a baby’s upper outer left or right arm.  At first, a BCG scar will look red, puffy and a bit moist or gooey.  Occasionally, a BCG can appear to ooze small amounts of fluid periodically during the first few months after administration.  However, once a BCG vaccine site heals, it looks like a very small flesh-colored scar.  In about 1 to 2% of babies (1 or 2 of every 100 babies), the BCG site will develop an abscess or cause swollen lymph nodes in the baby’s armpit.  Most of these abscesses will resolve or heal on their own without any treatment.  However, on rare occasions, a child may develop a secondary bacterial infection and require an oral antibiotic treatment.  If your child’s BCG site is extremely reddened, puffy, or oozing thick, colored or foul-smelling drainage, have your doctor or nurse practitioner examine your child. 

Should children who have been given a BCG be tested for TB?
YES, because BCG does not prevent pulmonary TB.  We have seen numerous cases where children with BCG vaccines have had positive findings of lung (pulmonary) TB disease.  Contrary to rumor and myth, having received one BCG vaccine does NOT mean a person will always have a false positive test.  However, timing of the TB test is important for babies or children who have been given BCG.  Persons with fresh, reddened or oozing BCG vaccine sites have a high probability of having a false positive TB Mantoux skin test.  However, once a BCG vaccine site appears to be well healed and flesh colored, a false positive test is unlikely.  Babies or young children who have had one BCG vaccination in the past that appears to be well-healed should be tested with a TB Mantoux test.  A reading of 10 mm or more of reddened induration (thickening or lump) should be considered positive. 

Children with a positive TB test should have chest films taken, to be sure they do not have active lung TB disease.  Most children who test positive will have a latent TB infection.  Latent TB means that a child was exposed to TB germs in the air, breathed in the germs and became infected without yet activating TB disease in the chest.  In order to prevent the TB germ from activating into lung disease, a child with latent TB should be treated for nine months with Isoniazid (INH).  Activation of the TB disease is more likely to occur in infants and toddlers, as compared to older children and adults.  About 40% of infants and toddlers with latent TB infection will develop actual TB disease in their lungs or lymph systems, as compared to about 15% of teens and adults who will eventually develop TB disease in the lungs or lymph system.

See also Tuberculosis in International Adoptees