2. 1. Bristol Medical School, University of Bristol
Beneficial effects of BCG vaccination in outcomes for patients diagnosed with TB: observational study using the Enhanced Tuberculosis surveillance system,
Sam Abbott1, Hannah Christensen1, Maeve K Lalor2, Dominik Zenner2, Colin Campbell2, Mary Ramsay2, Ellen Brooks-Pollock1
1. Bristol Medical School, University of Bristol
2. Public Health England

3. Background Tuberculosis in England BCG Vaccine
~ 6000 new cases notified each year
~ 70% of cases are Non-UK born
~ 40% of cases in London
BCG Vaccine
Variable effectiveness (0-80%)
Distance from equator acts a proxy for effectiveness
Protection wanes with time
In England, universal school age vaccination from 1953
Switched to targeted vaccination of high risk neonates in 2005
BCG vaccination and improved outcomes for active TB cases
Some evidence that BCG vaccination is associated with both reduced all-cause and TB-related mortality
BCG vaccination may reduce the burden of TB, leading to less severe active TB, and reduced infectiousness

4. Methods Data Source Enhanced Tuberculosis Surveillance (ETS) system
51,645 notifications
From:
In: England
Exposures
BCG vaccination status
Years since vaccination
Age at vaccination
Outcomes
All-cause mortality
TB mortality
Pulmonary disease
Smear status
Multiple episodes
Statistical Methods
Logistic regression
Univariable analysis
Multivariable analysis
Sensitivity Analysis
Multiply imputed data
Dropping recurrent cases
Restricting to those eligible for school age vaccination

5. Results All-cause Mortality BCG Vaccination
Complete case → aOR: 0.76 (95% CI: 0.64 to 0.89), P: 0.001
Multiple Imputation → aOR: 0.78 (95% CI: 0.62 to 0.97), P: 0.025
Years since Vaccination
Complete case → aOR: 0.91 (95% CI: 0.24 to 3.54) , P: 0.897
Multiple Imputation → aOR: 9.93 (95% CI: 2.4 to 41.13), P: 0.002
TB-related Mortality
BCG Vaccination
Complete case → aOR: 0.76 (0.51 to 1.13), P: 0.177
Multiple Imputation → aOR: 0.94 (95% CI: 0.56 to ), P: 0.807
Multiple Episodes
BCG Vaccination
Complete case → aOR: 0.90 (0.81 to 1.00), P: 0.056
Multiple Imputation → aOR: 0.91 (0.80 to 1.03), P: 0.129

6. Discussion
BCG vaccination was associated with improved outcomes for TB cases, particularly reduced all-cause mortality
Some evidence to suggest that the strength of these associations reduced after 10 years
Limitations
Generalizability of results
Comparability of populations
Missing data
Sample size
Strengths
Repurposing of routine data
Sensitivity analyses
Repeatability

7. Email: sam.abbott@bristol.ac.uk Website: samabbott.co.uk
Acknowledgements
This author was funded by the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Evaluation of Interventions at University of Bristol in partnership with Public Health England (PHE).  The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, the Department of Health or Public Health England.
Contact Details
Website: samabbott.co.uk