[1] Washington Univ, Sch Med, Dept Internal Med, St Louis, MO 63110 USA
[2] Washington Univ, Sch Med, Dept Pediat, St Louis, MO 63110 USA
[3] Univ Missouri, Dept Pharm Practice, Kansas City, MO 64110 USA
[4] St Louis Childrens Hosp, Virol Lab, St Louis, MO 63178 USA