SARS-CoV-2 antibodies in Ontario health care workers during and after the first wave of the pandemic: a cohort study

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.

Division of Infectious Diseases (Science, Allen, Kazmi, Liu, Sumaida), Department of Paediatrics, The Hospital for Sick Children; Public Health Ontario (Science, Bolotin, Schwartz); Dalla Lana School of Public Health (Bolotin, Ariyarajah), University of Toronto, Toronto, Ont.; Division of Infectious Diseases (Silverman), Department of Medicine and Department of Epidemiology and Biostatistics (Silverman), Western University, London, Ont.; Division of Infectious Diseases (Nadarajah), Markham Stouffville Hospital, Markham, Ont.; Department of Medicine (Nadarajah, Parekh, Leis), University of Toronto; SickKids Research Institute (Maguire, Schneiderman), The Hospital for Sick Children; Division of Nephrology (Parekh), Department of Pediatrics, The Hospital for Sick Children and University of Toronto; Department of Laboratory Medicine and Pathobiology (McGeer, Katz, Campigotto), University of Toronto; Lunenfeld-Tanenbaum Research Institute (McGeer), Sinai Health System, Toronto; Division of Infectious Diseases (Schwartz, Downing), Department of Medicine, Unity Health Toronto; Occupational Health and Safety (Alexander), The Hospital for Sick Children, Toronto, Ont.; Division of Infection Prevention and Control (Castellani), Sault Area Hospital, Sudbury, Ont.; Departments of Paediatrics and Molecular Genetics (Cohn), University of Toronto; Department of Paediatrics (Cohn), The Hospital for Sick Children; Division of Infection Prevention and Control (Katz), North York General Hospital; Division of Infectious Diseases (Leis), Sunnybrook Health Sciences Centre, Toronto, Ont.; Department of Pediatrics (Pernica), McMaster University, Hamilton, Ont.; Division of Microbiology (Campigotto), Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ont.