Abstract
Bacille Calmette–Guerin (BCG) vaccine is widely used as a prevention strategy against tuberculosis. BCG is a live vaccine, usually given early in life in most countries. While safe to most recipients, it poses a risk to immunocompromised patients. Several primary immunodeficiency diseases (PIDD) have been classically associated with complications related to BCG vaccine. However, a number of new inborn errors of immunity have been described lately in which little is known about adverse reactions following BCG vaccination. The aim of this review is to summarize the existing data on BCG-related complications in patients diagnosed with PIDD described since 2010. When BCG vaccination status or complications were not specifically addressed in those manuscripts, we directly contacted the corresponding authors for further clarification. We also analyzed data on other mycobacterial infections in these patients. Based on our analysis, around 8% of patients with gain-of-function mutations in STAT1 had mycobacterial infections, including localized complications in 3 and disseminated disease in 4 out of 19 BCG-vaccinated patients. Localized BCG reactions were also frequent in activated PI3Kδ syndrome type 1 (3/10) and type 2 (2/18) vaccinated children. Also, of note, no BCG-related complications have been described in either CTLA4 or LRBA protein-deficient patients; and not enough information on BCG-vaccinated NFKB1 or NFKB2-deficient patients was available to drive any conclusions about these diseases. Despite the high prevalence of environmental mycobacterial infections in GATA2-deficient patients, only one case of BCG reaction has been reported in a patient who developed disseminated disease. In conclusion, BCG complications could be expected in some particular, recently described PIDD and it remains a preventable risk factor for pediatric PIDD patients.
Highlights
Based on the World Health Organization (WHO) Global Tuberculosis Report, tuberculosis remains a public health global problem: it is the ninth leading cause of death worldwide, and the leading cause of death from a single pathogen [1]
The prevalence of Bacille Calmette–Guerin (BCG)-associated complications in the general population can vary widely depending on the reporting country, the vaccine strain used, and the age at vaccination
Reports of 1 in 2,500 vaccines presenting with localized BCG-associated complications, and 1 in 100,000 presenting with disseminated complications represent a fair estimate of the general prevalence of such side effects
Summary
Based on the World Health Organization (WHO) Global Tuberculosis Report, tuberculosis remains a public health global problem: it is the ninth leading cause of death worldwide, and the leading cause of death from a single pathogen [1]. Bacille Calmette–Guerin (BCG) vaccine is widely used as a prevention strategy against tuberculosis. The BCG vaccine was developed between 1908 and 1921. BCG was first administered to humans in 1921 and has been used for more than 95 years until now [2]. Vaccination policies vary around the world, linked mostly to tuberculosis disease prevalence. While tuberculosis endemic areas (mainly in developing countries) adopt universal vaccination, tuberculosis low-prevalence countries either restrict BCG vaccine to high-risk groups or choose not to administer it at all [3]. While BCG vaccine is believed to provide a somehow consistent protection against severe forms of tuberculosis (i.e., miliary, meningeal) in childhood, most adult individuals remain susceptible to pulmonary tuberculosis despite vaccination [4]. As previous exposure to nontuberculous mycobacteria (NTM) seems to influence vaccine efficacy, and to assure full coverage, BCG is usually given right after birth in the first months of life [5]
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