1. Department of Pediatrics and Adolescent Medicine and
2. Department of Medical Microbiology and Immunology
3. Department of Mathematics and Statistics, and
4. Department of Clinical Medicine, University of Turku, Turku, Finland
5. Department of Health Security, National Institute for Health and Welfare, Helsinki, Finland; and
6. Department of Medical Microbiology, Capital Medical University, Beijing, China
7. Department of Virology and Clinical Virology, Turku University Hospital and University of Turku, Turku, Finland