Affiliation: | Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden, Epidemiologic Surveillance and Response Unit, Department of Infectious Disease Surveillance and Control, National Institute of Health and Welfare, Helsinki, Finland and Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA. |