From the University of Maryland School of Medicine Center for Vaccine Development, Baltimore, Maryland.
Accepted for publication February 22, 2018.
The authors have no funding or conflicts of interest to disclose.
Address for correspondence: Kathleen M. Neuzil, MD, MPH, University of Maryland School of Medicine, 685 West Baltimore St. HSF1-Room 480, Baltimore, MD 21201. E-mail: firstname.lastname@example.org.