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

Angeliki Syggelou,Nikolaos Spyridis,Eleni Kourkouni,Irini Eleftheriou,Despoina Maritsi,Maria Tsagaraki,Maria Tsolia,Georgia Kourlaba,Kyriaki Benetatou

doi:10.3390/jcm9103224

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.

Highlights

The Bacille Calmette–Guérin (BCG) vaccine is currently the only licensed vaccine against tuberculosis (TB) and is included in the childhood immunization program in many countries
In a recent meta-analysis of studies that examined BCG-vaccinated and unvaccinated children who were exposed to TB with the use of IGRAs, it was shown that BCG protects against M. tuberculosis infection, as well as from progression to active disease [14]
The aim of the current study was to examine whether BCG vaccination has a protective role against latent TB infection (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)

Summary

Introduction

The Bacille Calmette–Guérin (BCG) vaccine is currently the only licensed vaccine against tuberculosis (TB) and is included in the childhood immunization program in many countries. This vaccine has been in use since 1921 and is the most widely used vaccine, with an estimated 100 million doses administered to neonates annually worldwide [1]. In a recent meta-analysis of studies that examined BCG-vaccinated and unvaccinated children who were exposed to TB with the use of IGRAs, it was shown that BCG protects against M. tuberculosis infection, as well as from progression to active disease [14]. New cases of childhood TB usually arise after contact with an infectious adult index case, and data highlight that, in the absence of intervention, up to 40% of children less than 2 years of age who have been infected will progress to active disease [13]

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