The Estonian H1N1 influenza 2009 outbreak was highly underestimatedSaar, Regina; Põdersoo, Diivi; Järvelaid, Mari; Tuubel, Linda; Suurväli, Jaanus; Nutt, Anu; Saaremäe, Merle; Saar, Tiiu; Rüütel Boudinot, SirjeProceedings of the Estonian Academy of Sciences2012 / p. 320-329 : ill