1. From the Department of Pediatrics, University of Florida College of Medicine, and the Department of Epidemiology, University of Florida College of Public Health and Health Professions and College of Medicine, Gainesville (S.A.R.); and the Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta (D.J.J.). Both authors were employed by the U.S. federal government until 2017 (D.J.J.) and 2018 (S.A.R.); both are currently unpaid guest researchers at the CDC.