1. Departments of Epidemiology, Biostatistics and Occupational Health and
2. Pediatrics, and
3. Department of Microbiology, Infectious Diseases and Immunology, Université de Montréal, Montreal, Canada and
4. Schulich Library of Physical Sciences, Life Sciences, and Engineering, McGill University, Montreal, Canada;
5. Department of Pediatrics, University of Alberta, Edmonton, Canada