[1] Univ Toronto, Hosp Sick Children, Dept Pediat, Div Pediat Emergency Med, Toronto, ON M5G 1X8, Canada
[2] McMaster Univ, Dept Family Med, Div Emergency Med, Hamilton, ON L8S 4L8, Canada
[3] Childrens Hosp, London Hlth Sci Ctr, Dept Pediat, London, ON, Canada
[4] Childrens Hosp, London Hlth Sci Ctr, Childrens Hlth Res Inst, London, ON, Canada
[5] Univ Western Ontario, Schulich Sch Med & Dent, London, ON, Canada
[6] Univ Toronto, Hosp Sick Children, Dept Pediat, Div Infect Dis, Toronto, ON M5G 1X8, Canada
[7] Univ Toronto, Hosp Sick Children, Dept Pediat, Div Pediat Emergency Med, Toronto, ON M5G 1X8, Canada