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Bacille-Calmette-Guerin, better known as B.C.G., is a living organism
related to the tubercle bacillus which can be injected into the skin without
causing tuberculosis and after a few weeks it produces a reaction, so that the
body tissues become sensitive to the toxin of the tubercle bacillus. This
special sensitivity is revealed by the fact that the tuberculin reaction
(Mantoux) is changed from negative to positive in four to six weeks after
administration of B.C.G.
Experience in other countries has shown that a person is less likely to
develop clinical tuberculosis if his Mantoux tuberculin reaction has been
converted from negative to positive, though this changed reaction does not
necessarily imply immunity from tuberculosis. In practice B.G.G. does
provide a considerable degree of safeguard against tuberculosis and the protection
can last for approximately six years By vaccinating with B.C.G.
children aged thirteen may obtain a degree of protection during the period of
adolescence when most vulnerable to pulmonary tuberculosis.
B.C.G. has been used in this country during recent years for exposed
susceptible groups of people such as nurses, medical students, and family
contacts of infectious tuberculosis cases. Also in selected areas, including
Tottenham, B.C.G has been given during the last three years to school leavers
in a trial survey conducted by the Medical Research Council.
The B C. G , is administered by injection of one drop into the skin to
children who are Mantoux negative. It is estimated that in this Area about
30% of thirteen years olds will be Mantoux Positive which means that such
children will already have had a very mild infection of tuberculosis sufficient
in most cases to give them protection against the disease. Children
who are strongly Mantoux Positive will have an X-ray of the chest to exclude
the presence of the disease.
There are two stages in the accepted procedure. First, a skin test to
see if B.C.G., vaccination is necessary. Secondly, the actual vaccination
when an injection is made into the skin.
There are about 2,400 children aged thirteen attending schools in
Tottenham and Hornsey, and on the assumption that 75% of parents will accept
vaccination with BGG., some 1,800 children will have to be skin-tested and
of these approximately 1,200 may need B.C.G.
Parents will be given an explanatory leaflet, general practitioners will
be informed and a short time before the vaccinating team visits a school the
parents will be invited to sign a consent form.
Skin tests will be carried out on Tuesdays and tests read on Fridays, when
negative reactors will receive an injection of the B.C.G. vaccine. The work
will be done during term time.