British Medical Journal
09 August 2014(vol 349, issue 7970)
http://www.bmj.com/content/349/7970

Research
Effect of BCG vaccination against Mycobacterium tuberculosis infection in children: systematic review and meta-analysis
A Roy, senior scientist1, M Eisenhut, consultant paediatrician2, R J Harris, statistician1, L C Rodrigues, professor of epidemiology3, S Sridhar, research associate4, S Habermann, junior doctor2, L Snell, junior doctor2, P Mangtani, senior lecturer3, I Adetifa, paediatrician and medical epidemiologist5, A Lalvani, professor of infectious disease4, I Abubakar, professor of infectious disease epidemiology16
Author affiliations
BMJ 2014; 349 doi: http://dx.doi.org/10.1136/bmj.g4643 (Published 05 August 2014) Cite this as: BMJ 2014;349:g4643
Accepted 11 July 2014
Abstract
Objectives
To determine whether BCG vaccination protects against Mycobacterium tuberculosis infection as assessed by interferon γ release assays (IGRA) in children.
Design
Systematic review and meta-analysis. Searches of electronic databases 1950 to November 2013, checking of reference lists, hand searching of journals, and contact with experts.
Setting
Community congregate settings and households.
Inclusion criteria Vaccinated and unvaccinated children aged under 16 with known recent exposure to patients with pulmonary tuberculosis. Children were screened for infection with M tuberculosis with interferon γ release assays.
Data extraction
Study results relating to diagnostic accuracy were extracted and risk estimates were combined with random effects meta-analysis.
Results
The primary analysis included 14 studies and 3855 participants. The estimated overall risk ratio was 0.81 (95% confidence interval 0.71 to 0.92), indicating a protective efficacy of 19% against infection among vaccinated children after exposure compared with unvaccinated children. The observed protection was similar when estimated with the two types of interferon γ release assays (ELISpot or QuantiFERON). Restriction of the analysis to the six studies (n=1745) with information on progression to active tuberculosis at the time of screening showed protection against infection of 27% (risk ratio 0.73, 0.61 to 0.87) compared with 71% (0.29, 0.15 to 0.58) against active tuberculosis. Among those infected, protection against progression to disease was 58% (0.42, 0.23 to 0.77).
Conclusions B
CG protects against M tuberculosis infection as well as progression from infection to disease.
Trial registration PROSPERO registration No CRD42011001698 (www.crd.york.ac.uk/prospero/).

Feature Infectious Diseases
Ebola: an opportunity for a clinical trial?
BMJ 2014; 349 doi: http://dx.doi.org/10.1136/bmj.g4997 (Published 06 August 2014) Cite this as: BMJ 2014;349:g4997
As the largest outbreak of Ebola virus has forced hitherto neglected tropical diseases on to the public agenda, debate is growing over whether affected patients should have the chance to try experimental drugs. Sophie Arie reports