He graduated in Medicine and Surgery at the University of Costa Rica and later specialized in Medical Oncology at the same university. He is doctor (PhD) in epidemiology at the Karolinska Institute, Sweden in 1996. He was coordinator of the «Natural history of cervical cáncer Study,» 1992-1995. From 1996 to 2000 he was an epidemiologist at the Field Studies Unit and Intervention of the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). From 2000 to 2011 he was the principal investigator of the » Phase III Vaccination against HPV 16 and 18 Study in Costa Rica.» From 1 June 2011 he joined the Early Detection and Prevention Unit of the International Agency for Research on Cancer (IARC) in Lyon, France. It is also noteworthy that Dr. Herrero has participated in more than 500 scientific publications.