The classical teaching is that BCG should be given at birth itself to safeguard the child from a delay which may result in infection in the interim period. However, there was a recent note(1) that BCG given at 6 months is less effective than that given at birth. Please clarify what is the difference in the protective efficacy of BCG vaccination given at 6 months of age as compared to it’s administration at birth?

Can BCG produce immune response if anti-tubercular chemotherapy is also simultaneously started? If it does, what is it’s immunologic basis?

Can BCG be given along with anti-tubercular chemotherapy in an unimmunized child suffering from tuberculosis, in the hope of inducing immune response and thus helping in better cure?

To what extent does mycobacterial infection from the environment affect the efficacy of BCG vaccination?

Does the Immunization Committee re-commend that tuberculin test must be done before immunizing a 6-month-old infant and why?

A. Santhoshkumar,
Assistant Professor,
SAT Medical College,
Thriuvananthapuram, India.

1. Amdekar YK. BCG vaccination with anti-tubercular therapy: Indian Pediatr 1998; 35: 1047-1048.

There are two reasons why BCG is given in the newborn. One is historical, in that BCG was originally used to protect babies born of mothers with open pulmonary tuberculosis. Those days antituberculosis drugs were not available. The vaccine had to be given as soon as possible after birth. Thus, the norm became BCG at birth, unchanged even after INH and other drugs became available. Today, the problem of untreated open pulmonary tuberculosis in the mother at delivery is not a major problem.

The second reason is that BCG vaccination is successful from birth, unlike several other vaccines. Obviously, that is also a very convenient timing from the viewpoint of contact with the health care system and we do not want to miss the opportunity. The proof of this principle is that BCG remains the best utilized vaccine (highest coverage achieved among all vaccines) under our national immunization program.

Dr. Santhoshkumar cites a statement that "Protective efficacy (of BCG) may be reduced if vaccinated at 6 months of age than at birth"(1). To the best of my knowledge, this statement is an error. It would be extremely difficult to investigate the differential of protective efficacy of BCG given at birth versus at 6 months. Most experts consider newborn age to be as good as later in infancy or childhood (not better), from the viewpoint of BCG take and tuberculin sensitization(2). I have not come across any expert saying that newborn age is better than later, from immunological angle. Let me quote from the textbook written by Dr. Seth: "it is recommended that BCG be given either at birth or at the time of earliest contact with the child, preferrably before 9 months of age and definitely by the time the child is an year old"(2).

The question of simultaneously giving BCG and INH therapy is to be clearly understood. The Indian BCG is sensitive to the drug INH. Again to quote Dr. Seth: "INH treatment during the course of vaccination lessens its protective effect"(2). When most experts say protective effect, they really mean immunological effect of tuberculin sensitization. However, if a newborn is at risk of infection from the mother with open pulmonary TB, should we not use both interventions, INH and BCG? This is done knowing that the immunizing effect of BCG might be (or is) less than that in children not on INH treatment. In many if not most instances, I am told, that BCG will take inspite of INH treatment. How does a drug sensitive microbe multiply in the face of the drug? My guess is that the drug level in the dermal tissue might be much lower than in more vascular layers of tissue. I have no personal experience, nor have I read any specific information on this issue. If the doctor is confident of good follow up of the family, certainly BCG could be delayed until after the drug is withdrawn. That will assure the best effect of both therapy and immunization.

There is no need for giving BCG to a child suffering from, or recovered from laboratory proven tuberculosis or with tuberculin sensi-tivity already induced by M. tuberculosis infection.

To what extent does infection by non-TB mycobacteria affect the efficacy of BCG? The Chingleput study showed no obvious effect(3). However, that study examined only the effect of BCG on secondary pulmonary TB and not on progressive or hematogenous spread of primary TB(3). The theoretical discussions on this issue do not help us. The main lesson is that we should ignore the effect of atypical mycobacteria on TB or on BCG.

Finally, even though the Immunization Committee has not made a specific recommendation, there is no particular need or advantage of tuberculin testing of infants at any age, before giving BCG. It has been shown that the likelihood of positive tuberculin reaction due to naturally occurring TB infection is no more than 2% below 5 years of age(3). Below 2 years it would be even less. There is no harm in giving BCG to a child who is already tuberculin reactive. Therefore, there is no need to test with tuberculin before giving BCG even up to 5 years of age. On the other hand, if preventive chemotherapy will be given to those who are tuberculin positive, then there could be justification for it. The present view of Indian experts is not to give routine preventive chemotherapy, but there is room for reviewing this in the light of the recent discussions on national TB control efforts(3).

T. Jacob John,
Emeritus Medical Scientist (ICMR),
439, Civil Supplies Godown Lane,
Kamalakshipuram, Vellore TN 632 002.
E-mail: [email protected]

1. Amdekar YK. BCG vaccination with anti-tubercular therapy: Reply. Indian Pediatr 1998; 35: 1047-1048.

2. Seth V. BCG Vaccination. In: Essentials of Tuberculosis in Children. Ed. Seth V. New Delhi, Jaypee Brothers, 1997; pp 35-47.

3. John TJ. Tuberculosis control, without protection from BCG. Indian Pediatr 2000; 37: 9-18.