[1] Univ Montreal, Dept Pediat, Ctr Hosp Univ St Justine, Montreal, PQ H3C 3J7, Canada
[2] Ctr Hosp Univ Montreal, Ctr Rech, Unite Immunovirol Mol, Montreal, PQ, Canada
[3] Univ Montreal, Dept Microbiol, Ctr Hosp Univ St Justine, Montreal, PQ, Canada
[4] Montreal Childrens Hosp, Dept Pediat, Montreal, PQ H3H 1P3, Canada
[5] Montreal Childrens Hosp, Dept Microbiol, Montreal, PQ H3H 1P3, Canada
[6] McGill Univ, Dept Epidemiol Biostat & Occupat Hlth, Montreal, PQ, Canada