Several researchers have studied the 1918 pandemic and estimated some of these key epidemiological parameters. Estimates have ranged from 2-3 for the basic reproductive number, R 0 , when using an SEIR model with a mean latent period of 1.9 days and infectious period of 4.1 days [13, 14] . Using an exponential model and assuming the serial interval to be four days (somewhat based on the assumptions of [13] ), [15] estimated R 0 to be 2.6-10.6 for confined settings (such as prison and ships) and 2.4-4.3 for community settings. The estimates for the mean latent and infectious periods come from [16] and were used again by [17] and [18] . It appears that the original estimates were derived from epidemic data, although their source is not well documented.