Study concept and design: Ford, Maynard.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Ford.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Ford.
Administrative, technical, or material support: Maynard.
Study supervision: Ford.
Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
Disclaimer: The findings and conclusions reported in this article are those of the authors and do not necessarily represent the official position of the US Centers for Disease Control and Prevention.