[1] Massachusetts Gen Hosp, Boston, MA 02114 USA
[2] Harvard Univ, Davis Ctr Russian Studies, Boston, MA 02115 USA
[3] Mechnikov State Med Acad, Infect Control Training Ctr, St Petersburg, Russia
[4] Mechnikov State Med Acad, Dept Epidemiol, St Petersburg, Russia
[5] First Childrens Hosp, St Petersburg, Russia
[6] Childrens Hosp, Boston, MA 02115 USA
[7] Harvard Med Int, Boston, MA USA