[1] McGill Univ, Ctr Hlth, Montreal Childrens Hosp, Div Pediat Emergency Med,Dept Pediat, 1001 Decarie Blvd, Montreal, PQ H4C 3J1, Canada
[2] Harvard Univ, Harvard TH Chan Sch Publ Hlth, Cambridge, MA 02138 USA
[3] Univ Toronto, Dept Pediat, Div Immunol & Allergy, Toronto, ON, Canada
[4] Hosp Sick Children, Toronto, ON, Canada
[5] Virginia Commonwealth Univ, Sch Dent, Richmond, VA USA
[6] Harvard Univ, Harvard Med Sch, Dept Pediat, Div Emergency Med, Boston, MA 02115 USA
[7] Boston Childrens Hosp, Boston, MA USA