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"Turning to the findings among the participants in the trial who were found to be tuberculin
positive at the first examination, and who were thus Ineligible for vaccination, more than 6 per 1000
had previously unsuspected lesions at this examination, in the majority of cases demonstrable by a
miniature chest radiograph. In Britain schoolchildren are usually regarded as an unprofitable group
for mass radiograph, because the prevalence of disease among them is relatively low, but it seems
from these findings that if the chest x-ray examinations were concentrated upon those tuberculin
positive they would be worthwhile. Such x-ray examinations of children found to be positive might
thus be a valuable adjunct to the present routine scheme for 13-year-olds in Britain; this procedure
had already been adopted by at least one large local authority.
"The contribution made to the incidence of tuberculosis by the tuberculin positive group did
not cease with the discovery of the 6 per 1,000 cases present initially. Tuberculosis has continued
to develop in this group throughout the period of observation. Indeed, the highest morbidity in any
group was noted among those who were the most highly sensitive at the outset: among those with
reactions of 15 m.m. or more to 3 T.U. the annual incidence was nearly 3 per 1,000.
"There are two main ways in which the continuing incidence in this highly tuberculin sensitive
and vulnerable group of schoolchildren might be reduced, or its effects ameliorated. The first is by
subsequent x-ray supervision. This would mean following up only a relatively small proportion of the
total skin-tested. There is also a suggestion from the preliminary results that the period of greatest
danger in this highly tuberculin sensitive group may not extend beyond two or three years after leaving
school, so that routine x-ray re-examination might be limited to this period. Even this may sound
unmanageable because of the large numbers involved, but with the reduction of tuberculous infection In
childhood these numbers might soon be less than at present. Even at its most effective, however, a
scheme of this nature serves only to detect tuberculosis, not to prevent it.
"The second way in which the continuing incidence of tuberculosis in this highly tuberculin
sensitive group might be reduced is to vaccinate at an earlier age before natural tuberculin sensitivity
has developed. Thus the age might be reduced too early in school life; a more comprehensive approach
would be to vaccinate in infancy. Infant vaccination should not merely prevent meningitis in early
childhood but might also reduce other cases of tuberculosis notified before and after leaving school.
There are, however, certain considerations which suggest caution in introducing mass vaccination in
infancy in Britain at the present time.
"First, there is the duration of protection afforded by vaccination. The evidence from the
trial so far is that it continues at least up to four years, while in the clinical trial of BCG among
American Indians by Aronson and his colleagues the protection did not show signs of waning until
after ten years, though the conditions in which that investigation was undertaken were admittedly
very different from those in this country. Hence, on present knowledge, if the vaccine were to be
given in Infancy tuberculin testing and re-vaccination in adolescence would have to be envisaged.
In other words, vaccination in infancy would have to be additional to, and could not replace, the
present scheme in adolescence.
"Secondly, there is the loss of the tuberculin test for epidemiological and diagnostic purposes.
These uses of the test are likely to become increasingly important as tuberculosis declines.
"Thirdly, there is a natural reluctance to add yet another immunisation procedure to those
already advised in infancy, unless the need is very obvious, In 1954, in England and Wales, about
2,000 cases of tuberculosis occurred before the age of 5 years. Among these were 212 cases of
meningitis. The provisional figures for 1955 show a reduction from those figures to 1,600 and 155
respectively. We have, therefore, to consider carefully whether these totals, coupled with the
decline in incidence, warrant the introduction of a vaccination scheme for over half a million infants
each year. We must however, appreciate that the numbers of cases notified in early childhood do not
give a comprehensive account of the dangers of tuberculous infection at that time, since tuberculous
infection in early life may give rise to some of the cases of tuberculosis notified in later life.
There is, therefore, clearly room for varying opinions about the advisability of introducing vaccination
for all Infants in Britain as a new policy."