[1] Vanderbilt Univ, Sch Med, Dept Pediat, Nashville, TN 37232 USA
[2] South Miami Hosp, Dept Pediat, Miami, FL USA
[3] Vanderbilt Univ, Sch Med, Dept Biostat, Nashville, TN 37232 USA
[4] Wake Forest Sch Med, Dept Pediat, Winston Salem, NC USA
[5] Wake Forest Sch Med, Dept Pediat Infect Dis, Winston Salem, NC USA