The "Spanish" influenza pandemic of 1918–1919,
which caused ≈50 million deaths worldwide, remains
an ominous warning to public health. Many questions
about its origins, its unusual epidemiologic features,
and the basis of its pathogenicity remain unanswered.
The public health implications of the pandemic
therefore remain in doubt even as we now grapple
with the feared emergence of a pandemic caused by
H5N1 or other virus. However, new information about
the 1918 virus is emerging, for example, sequencing
of the entire genome from archival autopsy tissues.
But, the viral genome alone is unlikely to provide
answers to some critical questions. Understanding the
1918 pandemic and its implications for future
pandemics requires careful experimentation and indepth
historical analysis