Virological surveillance of the Influenza A (H1N1)2009 pandemic: the role of the Belgian National Influenza Centre   , Gerard, C., Brochier Bernard, Quoilin Sophie, Wuillaume Françoise, Van Casteren Viviane, and Thomas Isabelle , Archives of Public Health, 0/0/2010, Volume 68, Issue 2, Number 75, p.68 - 75, (2010)