Interventions for Tuberculosis Control and Elimination 2002

Because BCG vaccination is given early in life, the protection afforded
is limited in time, and its effect on bacteriologically confirmed tuberculosis
in adults is inconsistent, it cannot be expected to have a great impact
on the epidemiology of tuberculosis. 858,859
It seems inappropriate to conclude from meta-analyses that BCG provides
some average protection. 791,792 The observed range in protection is
real and remains largely unexplained.
In light of the evidence, WHO recommends its use in newborn children
or as early in life as possible. 793,860 This is still sound policy for those
countries in the world where tuberculosis is highly prevalent, and tuberculous
meningitis is a frequent, disabling or fatal occurrence. It fails to
address the role of BCG where tuberculosis in children has become a rare
occurrence.
The IUATLD has developed recommendations on criteria for the discontinuation
of mass BCG vaccination. 861 Three key issues enter into the
decision making process on the discontinuation of BCG vaccination.
The first is the extent of protection BCG actually imparts in a given
location. In the USA, the low efficacy of BCG vaccination in Georgia,
Georgia-Alabama, and Puerto Rico had an important impact on the decision
not to routinely utilize BCG vaccination. As such prospective studies
are usually beyond the realm of resource availability, effectiveness
might alternatively be studied utilizing the case-control or contact study
approach.
The second is the frequency of serious forms of tuberculosis in children
(meningitis, disseminated forms) weighted against the frequency of
adverse reactions from the vaccine itself. This has been best studied in
Sweden where the frequency of serious adverse reactions from BCG vaccination
(osteoarticular and disseminated mycobacteriosis due to BCG) outweighed
the incidence of cases that the vaccine was intended to prevent
(figure 76). 703 Similarly, BCG vaccination may become non-cost-effective
as the frequency of childhood tuberculosis decreases, so that an increasing
number of children need to be vaccinated to prevent one case.
The third consideration is the value attached to the preservation of the
utility of the interpretation of tuberculin skin test results. BCG vaccination
induces tuberculin sensitivity and complicates the interpretation of tuberculin
skin testing results. In industrialized countries with an elimination
strategy in mind, the tuberculin skin test is an important means of identifying
persons with tuberculous infection at a high risk of progression to
tuberculosis who would benefit from preventive chemotherapy.
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