Does BCG Vaccination Protect Against Nontuberculous Mycobacterial Infection? A Systematic Review and Meta-Analysis

The incidence of non-tuberculous mycobacterial (NTM) infections is increasing worldwide, particularly NTM lymphadenitis and skin infections (Buruli ulcer). This review summarises the evidence for the protective effectiveness of Bacillus Calmette–Guérin (BCG) vaccination against NTM disease. A systematic search using PRISMA guidelines was done for controlled studies investigating the protective effectiveness of BCG vaccination against NTM disease in immunocompetent individuals. This revealed ten studies, including almost 12 million participants. Three cohort studies in industrialised countries suggest that the incidence of NTM lymphadenitis is greatly reduced among BCG-vaccinated children compared to BCG-unvaccinated children, with a risk ratio (RR) of 0.04 (95% confidence interval (CI) 0.01 to 0.21). In two randomised trials in low-income countries, BCG protected against Buruli ulcer for the first 12 months following vaccination, RR 0.50 (95% CI 0.37 to 0.69). Four case control studies had conflicting results. One cohort study found that individuals with Buruli ulcer are less likely to develop osteomyelitis if they have a BCG scar, RR 0.36 (95% CI 0.22 to 0.58). No studies have compared different BCG vaccine strains or the effect of revaccination in this setting.The protective effect of BCG vaccination against NTM should be taken into consideration when deciding on recommendations for discontinuation of universal BCG vaccination programs and in assessing new vaccines designed to replace BCG.