Miguel Ángel Luque-Fernández1, Elsa Negro Calduch2. 1. Biomedical Research Institute of Granada, University of Granada, Andalusian School of Public Health, Granada, Spain; London School of Hygiene and Tropical Medicine, Department of Epidemiology and Population Health, London, UK; Harvard T.H. Chan School of Public Health, Department of Epidemiology, Boston, MA, USA; Université Libre de Bruxelles, Public Health School, Centre de Recherche Épidémiologie, Biostatistique et Recherche clinique, Brussels, Belgium; CIBER of Epidemiology and Public Health (CIBERESP), Madrid, Spain. Electronic address: miguel-angel.luque@lshtm.ac.uk. 2. Independent Epidemiology Consultant, Cartagena, Spain.