BCG revaccination is still used in some tuberculosis endemic countries. Until now, the little evidence available suggested that BCG revaccination confers very limited additional protection, although there was no information on whether protection depends on the setting and age of revaccination, or if protection increases with time since vaccination. Here we report on an extended follow up of the BCG-REVAC trial, a cluster randomised trial conducted in the Brazilian cities Salvador and Manaus including over 200,000 children aged 7-14 years aimed to evaluate the efficacy of BCG revaccination in children who had received neonatal BCG vaccination. With the extended follow-up (9 years) and the additional cases accrued we now have enough power to report vaccine efficacy separately for the two cities (with different distances from Equator and presumably different prevalence of non-tuberculosis mycobacteria), and by age at vaccination and clinical form. The overall vaccine efficacy was 12% (-2 to 24%) as compared to 9% (-16 to 29%) for the 5-year follow up. Vaccine efficacy was higher in Salvador (19%, 3 to 33%) than in Manaus (1%, -27 to 27%) with the highest vaccine efficacy in children from Salvador aged <11 years at revaccination (33%, 3 to 54%). The findings are in line with the hypothesis that BCG vaccination offers higher efficacy in low NTMb prevalence, and show that revaccination with BCG can offer weak protection in selected subgroups.

The Center for Data and Knowledge Integration for Health (CIDACS) was created in 2016 in Salvador (Bahia, Brazil). This paper aims to present a profile of CIDACS, including its current databases. CIDACS aims to conduct interdisciplinary studies and research, develop new scientific methodology and promote professional training using linked large-scale databases and high-performance computational resources in a secure environment. Administrative data is at the core of the activities conducted by CIDACS. The advantages of administrative data include significantly larger sample sizes, an inherent longitudinal structure and high-quality information. The center’s research projects are primarily focused on enhancing the understanding surrounding the impact of social protection policies (e.g., public cash-transfer and housing programs) on health outcomes in low-income populations throughout Brazil. CIDACS’ primary data source is citizens who register with the Cadastro Único program, which encompasses individuals eligible to receive benefits from over 20 governmental social programs. CIDACS has two separate environments for data handling: 1) Data Production Center, a secure room housing the computational infrastructure for ingesting, storing, cleaning, processing and linking original databases, as well as extracting research-ready datasets and 2) Data Analysis Environment, a computational infrastructure based on data safe haven principles, which allows researchers to access and process requested datasets. Brazil has a large public health community that uses national health and social databases for research programs, and the linkage of different databases has been a widely employed practice in the country. CIDACS is the result of efforts by researchers, policymakers and public health officials to use and improve the quality of Brazilian health databases. CIDACS is expected to be an important resource for researchers and policymakers interested in improving the evidence base in different aspects of health, as well as with regard to the social determinants of health and the effects of social and environmental policies on health in general.

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