Interventions for Tuberculosis Control and Elimination 2002

Haiti
N. Am. Indians
Madanapelle
Muscogee / Russell
Muscogee
Chingleput
Illinois
Muscogee
85 with a BCG scar did so. 788 While considerable attention was paid to
adjustment for potential confounding factors (yet the effect remained), the
authors were still cautious in concluding that BCG vaccination reduces case
fatality from pulmonary tuberculosis.
Hypotheses about the variation in the efficacy of BCG
vaccination
While the overall evidence is quite clearly in favor of a protective effect
of BCG vaccination, the observed variations are large in both prospective
and retrospective studies. A number of hypotheses have been formulated
to address these discrepancies. Smith 789 and Smith and Fine 790 have comprehensively
reviewed the evidence, and the following outline is guided by,
and draws heavily on, their assessment.
The principal hypotheses to explain the variations observed in the protection
offered by BCG include:
• Differences in methodological stringency;
• Differences in vaccine strains;
• Differences in vaccine dose;
-400 -100 0 30 50 80 90 95
Per cent protection
115
All forms
All forms
All forms
All forms
All forms, 5-28 yr,
10-yr follow-up
Pulmonary,
Culture confirmed
Mental institutions
All forms, 5-28 yr,
10-yr follow-up
Figure 71. Results from prospective studies on the efficacy of BCG vaccination
against tuberculosis in all ages. 738,763-765,767,768,781-787