Dr Josh Osowicki is a Paediatric Infectious Diseases physician at the Royal Children’s Hospital and leads the Vaccine Challenges team in the Tropical Diseases Research Group at the Murdoch Children’s Research Institute, in Melbourne. Josh has a Janus-faced career as a clinician-scientist, aiming to cure human infections in his clinical work and to deliberately cause them in his research (safely and for science)! With an international team, he and Prof. Andrew Steer led development of the world’s only Streptococcus pyogenes pharyngitis human infection model in the CHIVAS-M75 study. The human model was recently used for the CHIPS trial, informing development of improved penicillin formulations, and has become a focal point for vaccine development activities and research. Josh is working with every major developer towards human challenge trials to evaluate their Strep A vaccine candidate/s and projects to explore correlates of immune protection and novel immunoassays. He will shortly lead a trial to expand the S. pyogenes experimental human infection ecosystem by introducing a new strain into the pharyngitis model, from the M1uk lineage which has recently emerged as the leading cause of severe invasive infections. He is also collaborating on development of new human models of Neisseria gonorrhoeae, Staphylococcus aureus, and Mycobacterium ulcerans.