1. From the Department of Clinical Microbiology, Infectious Diseases (A.-M.C.-A., E.H., C.A.) and Department of Public Health and Clinical Medicine, Sunderby Research Unit (M.E., L.H.), Umeå University, Umeå, Sweden; Department of Mathematics and Statistics, The Open University, Milton Keynes, UK (H.W.); and Department of Medicine, Center for Infectious Medicine, Karolinska Institutet, Huddinge, Sweden (J.K.).