1. ICONA Foundation , Milan , Italy
2. Clinical and Research Infectious Diseases Department, National Institute for Infectious Diseases Lazzaro Spallanzani IRCCS , ICONA Foundation, via A. di Rudinì 8, 20142, Rome , Italy
3. Centre for Clinical Research, Epidemiology, Modelling and Evaluation (CREME), Institute for Global Health, University College London , London , UK