Potential conflicts of interest. K. C. B., A. V., and C. G. had a role as a Medical Advisor of Encephalitis 411 (unpaid). K. C. B. and A. V. report unpaid participation on a Data Safety and Monitoring Board for the French Dex Enceph Study. A. V. received payment for expert testimony as an expert witness for the Vaccine Injury Compensation Program and an expert witness for medicolegal cases; travel support partly paid directly to the author for the UK Encephalitis Society Annual Meeting; and an unpaid role as a scientific advisory panel member, UK Encephalitis Society. D. G. received research reagents from Illumina, Inc, and IDbyDNA, Inc; serves on the Scientific Advisory Board for bioMerieux; reports grants or contracts from the Fisher Center Discovery Program, Johns Hopkins; and payment or honoraria for lectures, presentations, speaker’s bureaus, manuscript writing, or educational events from the American Association of Clinical Chemistry and Pan American Society of Clinical Virology. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.