1. Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut
2. Department of Biostatistics, Yale School of Public Health, New Haven, Connecticut
3. Department of Bacteria, Parasites and Fungi, Statens Serum Institut, Copenhagen, Denmark
4. Department of Pediatrics, Yale School of Medicine, New Haven, Connecticut
5. Infectious Disease Epidemiology and Prevention, Statens Serum Institut
6. Department of Infectious Diseases and Pulmonary Medicine, Nordsjaellands Hospital, Copenhagen University Hospital, Denmark