The Spanish flu of 1918 may have killed more people than the first world war.

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As a comparison, the Spanish flu of 1918, in which 40 million people died, had only about 2-3 % kill-rate.

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We exchanged letters every Christmas until he passed away in the flu epidemic of 1918.

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During the flu pandemic of 1918, cases began in the spring and then faded away during the summer, only to come back with a vengeance in the fall and winter.

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Nevertheless, the last four pandemics - the Spanish Flu that began in 1918, the Asian Flu of 1957, the Hong Kong Flu of 1958 and the swine flu of 2009 - were all preceded by periods of La Nina conditions.

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Last year, however, Simonsen and Viggo Andreasen concluded that the true R-naught of the 1918 flu virus was probably somewhere between 3 and 4.

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Medical historians believe that a large proportion of those who died of the Spanish flu pandemic in 1918 were not killed by the flu virus, but by secondary bacterial pneumonia, which was difficult to treat before the introduction of antibiotics.

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By contrast, the 1918 flu pandemic that killed 50 million had an incubation period of two days (and an R of 2).

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