Effect of BCG vaccination against Mycobacterium tuberculosis infection in children: systematic review and meta-analysis - Roy, A; Eisenhut, M; Harris, RJ; Rodrigues, LC; Sridhar, S; Habermann, S; Snell, L; Mangtani, P; Adetifa, I; Lalvani, A; Abubakar, I (BMJ: British Medical Journal, 2014)