[1] Wake Forest Univ, Off Global Hlth, Bowman Gray Sch Med, Med Ctr Blvd, Winston Salem, NC 27157 USA
[2] Wake Forest Univ, Sect Infect Dis, Bowman Gray Sch Med, Winston Salem, NC 27157 USA
[3] West Virginia Univ, Dept Family Med, Morgantown, WV 26506 USA
[4] Wake Forest Univ, Dept Biol, Winston Salem, NC 27109 USA
[5] Carolina Dept Hlth & Human Serv, Div Publ Hlth, Immunizat Branch, Raleigh, NC 27609 USA