1. Department of Infectious Diseases1 and Department of Medical Microbiology3, Center for Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands 2MucoVax bv, Niels Bohrweg 11–13, Leiden, The Netherlands 4Department of Medicine, Division of Infectious Diseases, University of Pittsburgh, USA 5Department of Internal Medicine, Bronovo Hospital, Bronovolaan 5, The Hague, The Netherlands