AUTHOR CORRECTION
Volume 53, no. 4, p. 1406–1410, 2015. Page 1410: The following should be inserted at the end of the sole paragraph in the Acknowledgment section. “The information presented in this article and its supplemental material reflects years of effort coordinated within the CDC with U.S. interagency partners and the World Health Organization. The Department of Homeland Security (DHS) sponsored production of a portion of this material under an interagency agreement with the DHS Science and Technology Directorate. We acknowledge the Health and Human Services Biomedical Advanced Research and Development Authority and the CDC Office for Public Health Preparedness and Response for additional funding. All research was conducted with approval from the World Health Organization Advisory Committee on Variola Virus Research.”