Thai researchers and clinicians have long been in the forefront of efforts to better understand and treat dengue infections and the Faculty of Tropical Medicine has played a particularly key role over the years, perhaps most notably in what is the single most important development in the field of dengue research in the last decade: 2015 saw the commercial licensure of the world’s first dengue vaccine, Dengvaxia (CYD-TDV), a live recombinant tetravalent dengue vaccine developed by the company Sanofi Pasteur. A safe, effective and affordable vaccine against dengue has been long-sought and progress in bringing it about has been fraught with difficulty, but fortunately the goal has been achieved and the Faculty of Tropical Medicine played an important role in making it happen. Researchers from the Department of Clinical Tropical Medicine, the Department of Tropical Pediatrics and the Vaccine Trial Center, under Professor Dr. Punnee Pitisuttithum, together played a key role in testing the vaccine in Thai children between the ages of 2 and 16 years, conducting trials that found the dengue vaccine to be safe, moderately efficacious, with an overall 81% reduction in risk of severe dengue infection. The Dengvaxia vaccine is now on the market for use in children over 9 years old in Mexico, Brazil, and the Philippines, and should become available in Thailand sometime in 2016.