1. Department of Medical Epidemiology and Biostatistics; Karolinska Institutet; Stockholm Sweden
2. Clinical Epidemiology Division, Department of Medicine, Solna; Karolinska Institutet and Karolinska University Hospital; Stockholm Sweden
3. Department of Statistics; University of Florida; Gainesville FL
4. Department of Biostatistics, School of Public Health; University of Washington; Seattle WA
5. Vaccine and Infectious Diseases Division; Fred Hutchinson Cancer Research Center; Seattle WA
6. Center for Inference and Dynamics of Infectious Diseases; Seattle WA