University of Wisconsin - Madison - Influenza Research Institute, University of Wisconsin-Madison - Influenza Research Institute, University of Wisconsin-Madison - Influenza Research Institute, University of Wisconsin Hospital and Clinics - UW Health Clinical Laboratories, University of Michigan at Ann Arbor - Department of Pathology, University of Michigan at Ann Arbor - Department of Epidemiology, University of Wisconsin-Madison - University of Wisconsin Hospital and Clinics, University of Michigan at Ann Arbor - Department of Epidemiology and University of Wisconsin-Madison - Influenza Research Institute