[1] Univ Iowa, Dept Epidemiol, Coll Publ Hlth, 145 N Riverside Dr,S400 CPHB, Iowa City, IA 52242 USA
[2] Univ Saskatchewan, Dept Community Hlth & Epidemiol, Saskatoon, SK, Canada
[3] Univ Washington, Harborview Injury Prevent & Res Ctr, Dept Pediat, Seattle, WA USA
[4] Univ Sci & Technol China, Inst Publ Hlth Sci, Div Life Sci & Med, Hefei 230026, Anhui, Peoples R China
[5] Univ Wisconsin, Div Infect Dis, Sch Med & Publ Hlth, Madison, WI USA