Beneficial effects of BCG vaccination in outcomes for patients with active TB: observational study using the Enhanced Tuberculosis surveillance system 2000-2014

Abstract

Bacillus Calmette–Guérin (BCG) is one of the mostly widely-used vaccines and the only vaccine that protects against tuberculosis (TB) disease. However, little attention has been given to the indirect benefits of BCG. We aimed to quantify the effects of BCG vaccination on outcomes for individuals with notified TB in England and Wales to provide evidence for appropriate public health action and provision. We obtained all TB notifications for 2000-2014 in England and Wales from the Enhanced Tuberculosis surveillance system. We considered six outcomes: pulmonary disease, smear status, drug resistance, multiple episodes, all-cause mortality, and successful treatment. We used logistic regression to investigate each outcome with BCG vaccination, years since vaccination and age at vaccination, adjusting for potential confounders. We conducted multiple sensitivity analyses to assess the robustness of our results, using multiply imputed data, by dropping each covariate in turn, and varying our definitions of successful treatment and mortality.We found evidence of associations between BCG vaccination and increased successful treatment (aOR: 1.14 (1.04-1.25), P:0.004), reduced mortality (aOR: 0.78 (0.66-0.93), P:0.006), and reduced multiple episodes (aOR: 0.86 (0.77-0.96), P:0.007). We found no evidence of associations with drug resistance, pulmonary TB or sputum smear status. There was little evidence of associations between years since vaccination and TB outcomes. However, there was some evidence that age at vaccination was associated with mortality (P:0.048), multiple episodes (P:0.097), and successful treatment (P:0.048); with a beneficial effect of vaccination at 12 to < 16 years compared to at birth for mortality (aOR: 0.61 (0.33-1.11)), successful treatment (aOR: 1.35 (0.98-1.86)), and multiple episodes (aOR: 0.72 (0.49-1.06)).Our results indicate that BCG vaccination may be effective in preventing negative outcomes associated with TB disease; this evidence should be considered in future cost-effectiveness studies of BCG vaccination.

Date
Location
Warwick, United Kingdom
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