A systematic review of BCG vaccination policies among high-risk groups in low TB-burden countries: implications for vaccination strategy in Canadian indigenous communities

Abstract

BackgroundBacille Calmette-Guérin (BCG) vaccination against tuberculosis (TB) is widespread in high-TB-burden countries, however, BCG vaccination policies in low-burden countries vary. Considering the uncertainties surrounding BCG efficacy and the lower likelihood of TB exposure in low-incidence countries, most have discontinued mass vaccination, choosing instead a targeted vaccination strategy among high-risk groups. Given the increased risk of TB infection in Canadian Indigenous communities compared to the general Canadian population, these communities are a pertinent example of high-incidence groups in an otherwise low-burden country, warranting particular consideration regarding BCG vaccination strategy. This systematic review aims to synthesise and critically appraise the literature on BCG vaccination strategies in high-risk groups in low-incidence settings to provide policy considerations relevant to the Canadian Indigenous context.Methods: A literature search of the Medline and Embase databases was conducted, returning studies pertaining to BCG vaccine efficacy, TB incidence under specific vaccination policies, BCG-associated adverse events, and vaccination policy guidelines in low-burden countries. Study screening was tracked using the Covidence systematic review software (Veritas Health Innovation, Melbourne, Australia), and data pertaining to the above points of interest were extracted.ResultsThe final review included 49 studies, spanning 15 countries. Although almost all of these countries had implemented a form of mass or routine vaccination previously, 11 have since moved to targeted vaccination of selected risk groups, in most cases due to the low risk of infection among the general population and thus the high number of vaccinations needed to prevent one case in the context of low-incidence settings. Regarding identifying risk groups for targeted screening, community-based (rather than individual risk-factor-based) vaccination has been found to be beneficial in high-incidence communities within low-incidence countries, suggesting this approach may be beneficial in the Canadian Indigenous setting.ConclusionsCommunity-based vaccination of high-incidence communities may be beneficial in the Canadian Indigenous context, however, where BCG vaccination is implemented, delivery strategies and potential barriers to achieving adequate coverage in this setting should be considered. Where an existing vaccination program is discontinued, it is crucial that an effective TB surveillance system is in place, and that case-finding, screening, and diagnostic efforts are strengthened in order to ensure adequate TB control. This is particularly relevant in Canadian Indigenous and other remote or under-served communities, where barriers to surveillance, screening, and diagnosis persist.

Further Evidence of a Possible Correlation Between the Severity of Covid-19 and BCG Immunization

“…Especially the availability, consistency and reliability of historical data and statistics on the administration of immunization programs in the national, regional and so on, jurisdictions can be an issue. (4) Used in targeted communities with higher incidence (5) Limited age cohort (Quebec: 19 years, Spain: 16 years) (6) Immunization started at later age (not at birth) (7) Contradictory data on immunization practice (at birth or later age).…”

Visual impairments among immigrants living in Northeast Turkey and their ocular finding differences compared to the local population

“…Although a routine vaccination program exists in almost all countries regarding TB, these individuals with low socioeconomic status could have difficulties in accessing the vaccination program, and many do not know whether Bacillus Calmette-Guérin (BCG) vaccination has been administered. [17][18][19][20] Blepharitis is one of the most common infestations in routine ophthalmology practice, and in our study, this situation was higher in immigrant individuals than in the local population.Among the patients in the study, the rates of glaucoma, ARMD and diabetic retinopathy were higher in patients in the local population than in immigrant patients. While Table 1.…”

Comparison of Latent Tuberculosis Infections among General versus Tuberculosis Health Care Workers in Myanmar

“…This was not the case in our study, mainly because of the low percentage of exposure in both groups. BCG vaccination has been known to cause a false positive TST result, and to have a limited protective effect on TB [ 23 , 24 ]. Our data, through univariate analysis, suggest that those vaccinated were less likely to have a positive TST result.…”