BCG Vaccine Protection against TB Infection among Children Older than 5 Years in Close Contact with an Infectious Adult TB Case

Abstract

The Bacille Calmette–Guérin (BCG) vaccine has been shown to provide considerable protection against miliary or meningeal tuberculosis (TB), but whether it prevents other forms of disease remains controversial. Recent evidence has shown that the BCG vaccine also provides protection against latent TB infection (LTBI). The aim of the current study was to examine whether BCG has a protective role against LTBI among children in close contact with an adult index case in a low TB endemicity setting with the use of the QuantiFERON-TB Gold In-Tube test (QFT-GIT). A cross-sectional study was conducted over a 10-year period among children referred to our outpatient TB clinic with a history of close contact with an adult with pulmonary TB. All subjects had a QFT-GIT performed. In total, 207 children > 5 to 16 years of age with known recent exposure were enrolled. BCG-vaccinated subjects had a 59% lower risk of presenting with LTBI after close contact with an adult index case compared with unvaccinated subjects (OR = 0.41, 95% CI: 0.23–0.73, p = 0.002). After adjustment for possible confounders, the protective effect of prior BCG immunization was estimated at 68% (OR = 0.32, 95% CI: 0.15–0.66, p = 0.002). Other risk factors for LTBI included a history of migration (OR = 2.27, 95% CI: 1.13–4.53, p = 0.021) and transmission of infection to other exposed child contacts (OR = 4.62, 95% CI: 2.27–9.39, p = 0.001). We were able to determine a strong protective role of BCG vaccination among children older than 5 years, immunized at school entry, who had close contact with an adult infectious TB case.

Effect of BCG vaccination against tuberculosis infection in Young immigrants: a systematic review and meta-analysis

“…This systematic review and meta-analysis aimed to test if BCG vaccination could protect young people, especially young immigrants, against tuberculosis infection and reinforced recent research on this topic. Previous research done in Indonesia (a high-prevalence country) showed that BCG protection against TB infection was around 48% among examined young children (95% confidence interval 19% to 67%) 8 . Another research done in Greece (a low-prevalence country) represented that BCG protection against TB infection was around 19% among examined young children (95% confidence interval 8% to 29%) 8 .…”

“…Previous research done in Indonesia (a high-prevalence country) showed that BCG protection against TB infection was around 48% among examined young children (95% confidence interval 19% to 67%) 8 . Another research done in Greece (a low-prevalence country) represented that BCG protection against TB infection was around 19% among examined young children (95% confidence interval 8% to 29%) 8 . Research results showed that BCG vaccines would help protect adolescents from TB infections.…”

“…Research results showed that BCG vaccines would help protect adolescents from TB infections. Scientists indicated that immigrating from foreign countries would be a risk factor for young children infected by TB 8 . Statistics included in this review showed that young immigrants from countries with low TB risk levels would have higher BCG vaccination rates and lower infection rates than those with high TB risk levels 5 .…”

Nanocarriers in Tuberculosis Treatment: Challenges and Delivery Strategies

“…The current vaccination used to prevent TB is called Mycobacterium bovis bacillus Calmette-Guérin (BCG), and it was first given out in 1921 [35]. The BCG vaccine protects against TB in children between 60 and 80 percent of the time, but it is ineffective against pulmonary TB in adults [36]. Instead of the BCG vaccine, which is only effective in children, the WHO advises pharmacological therapies for TB in adults; their efficacy has also been reported to differ geographically [37].…”

Adjuvants and Antigen-Delivery Systems for Subunit Vaccines against Tuberculosis

“…In 1974, the World Health Organization included BCG in its list of vaccines recommended for the Expanded Program on Immunization [ 4 ]. Currently, BCG is administered to more than 100 million neonates per year and provides about 50% protection against clinical TB in children [ 5 ]. However, BCG is a live vaccine, and its administration leads to infection in about 1:10,000 to 1:1,000,000 children [ 6 ].…”