**6. Conclusions**

What are the lessons learned and the next steps?

Four lessons were learned during the STCC saga—#1: the harmonious interaction between the clinical and basic research teams is essential to allow translational research to proceed; # 2: even in the pre-clinical phase, it is essential to identify potential suppliers in the market for the formulations that are intended to be used as treatment and/ or industry partners interested in leading the product to the market; #3: the inclusion of master's and doctoral students should only be done in pre-clinical studies. In clinical trials, the stable inclusion of trained and mature professionals, economically stable, is necessary to avoid the shortage of human resources during the study; #4: a national and international network of experts is critical to overcoming the numerous doubts that arise in such a long study. In this case, we learned a lot about the clinical use of Se during the 15 years of the clinical trial, and we continue to learn about the physiopathology and clinical management of patients with Chagas disease.

Concerning the next steps, we are at the stage of preparing the reports for the sponsors and for our patients participating in the study. We will have several consequences in the clinical scope:


As a second initiative, we will prepare a dossier for the National Commission of Technology Incorporation in the Health System (Comissão Nacional de Incorporação de Tecnologias no SUS" – CONITEC) to evaluate the recommendation of dietary supplementation for patients with Chagas disease with Se, either by supplementation with one Brazil nut per day (about R \$20 per month) or by supplementation with Se and Coenzyme Q10 (about R\$80 per month), due to type B levels of evidence for therapeutic studies in the literature and the safety when administering Se to elderly persons [25–27].

Last, but not least, we intend to incorporate Chagas Express XXI as cutting-edge educational technology, since we have already demonstrated its potential as an instrument of field epidemiology. In the next expeditions planned for 2022 in the states of Pernambuco, Goiás, and Minas Gerais, we will include a rapid test for a local screening of positive people and inclusion in the National Health System for diagnostic confirmation and clinical follow-up. We will also include a local digital electrocardiogram to screen for possible abnormalities related to Chagas disease in individuals with mild cardiac form/stage A. The Chagas Express XXI is a potentially useful social technology for health and science education and active search for chronic cases of disease of asymptomatic CD patients, contributing to the notification of chronic cases and their inclusion in the lines of care of PCDT-Chagas. Furthermore, this technology can be adapted to understand and cooperate in other potentially epidemic situations, especially related to other neglected diseases, such as leishmaniasis, tuberculosis, and arboviruses.
