Sergio earned his medical degree in 1989 and his PhD in 2006, both from the University of Buenos Aires, Argentina. He completed his pediatric residency in 1993, his clinical immunology fellowship in 1996, and was an attending immunologist until 2008, all at the National Pediatric Hospital, in Buenos Aires, Argentina. In 2009 he was appointed Chief, Infectious Diseases Susceptibility Unit, LHD, and Co-Director, PID-Clinic, NIAID, NIH and in 2013 he joined the DLM, NIH Clinical Center, where he serves as the Chief of the Immunology Service