1 Public Health Ontario (Johnstone, Patel); Dalla Lana School of Public Health (Johnstone), University of Toronto; Department of Laboratory Medicine and Pathobiology (Patel), University of Toronto, Toronto, Ont. johnstone@oahpp.ca.
2 Public Health Ontario (Johnstone, Patel); Dalla Lana School of Public Health (Johnstone), University of Toronto; Department of Laboratory Medicine and Pathobiology (Patel), University of Toronto, Toronto, Ont.