Truth, double truth and statistics.

After every influenza pandemic (including the Russian of the 1890s and the Spanish influenza of 1918–1919), learned commentaries have reflected on the clinical presentation of the disease, noting that the great majority of cases were very mild, so mild that they corresponded much more to the symptoms of an upper respiratory tract infection than to an influenza-like illness with fever and prostration.1 This seems to fly in the face of modern pronouncements such as that by Glass in 2004 that pandemic flu was more than a ‘perceived threat’ but rather a ‘real killer’.2