1. National Institute of Cardiology and Cardiovascular Surgery, Havana, Cuba
2. Clinical Trial Service Unit and Epidemiological Studies Unit (CTSU), Nuffield Department of Population Health, University of Oxford, Oxford, UK
3. MRC Population Health Research Unit, University of Oxford, Oxford, UK
4. Institute of Hygiene, Epidemiology and Microbiology, Cuban Ministry of Public Health, Havana, Cuba
5. Provincial Centre of Hygiene, Epidemiology and Microbiology, Matanzas, Cuba
6. Municipal Centre of Hygiene, Epidemiology and Microbiology, Jagüey Grande, Matanzas, Cuba
7. Municipal Centre of Hygiene, Epidemiology and Microbiology, Colón, Matanzas, Cuba
8. Municipal Centre of Hygiene, Epidemiology and Microbiology, Camagüey, Camagüey, Cuba