1 Marshfield Clinic Research Institute, Marshfield, WI, United States.
2 Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.
3 School of Public Health, University of California, Berkeley, CA, United States.
4 Department of Pediatrics, Duke University School of Medicine, Durham, NC, United States.
5 Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States. Electronic address: Nancy_Bennett@urmc.rochester.edu.