Bacillus Calmette-Guérin vaccine protects against Mycobacterium tuberculosis infection and progression from infection to disease, according to findings published in The British Medical Journal.
Researchers from the Centre for Infectious Disease Surveillance and Control in London conducted a systematic review and meta-analysis of 14 studies in which children aged 16 years and younger were screened during a tuberculosis outbreak, referred to the hospital as a close contact of a case, or were household contacts of an adult case. Studies published between 1950 and 2013 were included in the analysis and included 3,855 participants. Bacillus Calmette-Guérin (BCG) vaccination status was determined by BCG scar, medical records and parental confirmation.
The overall risk ratio was 0.81 (95% CI, 0.71-0.92), which indicated a 19% protective efficacy among children vaccinated after exposure compared with unvaccinated children, according to the researchers. Protection efficacy did not differ between the two types of interferon gamma release assays (ELISpot or QuantiFERON).
Subgroup analysis showed studies conducted above 40° latitude found BCG vaccination had a protective efficacy of 26% (RR=0.74; 95% CI, 0.6-0.91), while studies conducted at lower latitudes of 20° to 40° (RR=0.88; 95% CI, 0.54-1.45) and 20° to 0° (RR=0.87; 95% CI, 0.72-1.04) had no protective effect.
“Our results provide evidence that BCG protects against tuberculosis infection from multiple epidemiologically different settings and independent of the type of interferon Y release assay used to detect infection. Future trials of candidate vaccines need to investigate the efficacy of the new vaccine against tuberculosis infection and early progression and late progression to active disease,” the researchers concluded.
Disclosure: The researchers report no relevant financial disclosures.