1. Centre for Research in Infectious Diseases, National Institute of Respiratory Diseases, Calzada de Tlalpan 4502, Colonia Sección XVI, CP 14080 Mexico City, Mexico
2. Hospital General de Tijuana, Av. Centenario 10851, Zona Río, C.P. 22320 Tijuana, B.C., Mexico
3. CAPASITS Cancún. 65, andador 5 entre calle 12 y 13, atrás del Hospital General de Cancún, C.P. 77500 Col. Centro. Cancún, Quintana Roo, Mexico
4. Condesa Specialised Clinic, General Benjamín Hill 24, Colonia Condesa, CP 06140 Mexico City, Mexico