title: Epidemiology and transmission dynamics of the 1918-19 pandemic influenza in Florence, Italy.
abstract: To investigate the 1918/19 influenza pandemic daily number of new hospitalizations in the only hospital in Florence (Central Italy) were analyzed. In order to describe the transmission dynamics of the 1918/1919 pandemic influenza a compartmental epidemic model was used. Model simulations show a high level of agreement with the observed epidemic data. By assuming both latent and infectious period equal to 1.5 days, the estimated basic reproduction number was R(0)(1) = 1.03 (95% CI: 1.00-1.08) during the summer wave and R(0)(2) = 1.38 (95% CI: 1.32-1.48) during the fall wave. Varying the length of the generation time or the estimation method, R(0)(2) ranges from 1.32 to 1.71. The hospitalization rate was found significantly different between summer and fall waves. Notably, the estimated basic reproductive numbers are lower compared to those observed in other countries, while the age distribution of deaths resulted to be consistent with the patterns generally observed during of the 1918-1919 pandemic. Our knowledge on past pandemics, as for the 1918-19 Spanish influenza, would help improving mathematical modeling accuracy and understanding the mechanisms underlying the dynamics of future pandemics.
authors.affiliation: National Centre for Epidemiology Surveillance and Health Promotion, Istituto Superiore di Sanità, Viale Regina Elena, 299 Rome, Italy. caterina.rizzo@iss.it
authors.forename: Caterina
authors.initials: C
authors.lastname: Rizzo
authors.forename: Marco
authors.initials: M
authors.lastname: Ajelli
authors.forename: Stefano
authors.initials: S
authors.lastname: Merler
authors.forename: Andrea
authors.initials: A
authors.lastname: Pugliese
authors.forename: Ilaria
authors.initials: I
authors.lastname: Barbetta
authors.forename: Stefania
authors.initials: S
authors.lastname: Salmaso
authors.forename: Piero
authors.initials: P
authors.lastname: Manfredi
mesh_terms: D017677:Age Distribution; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology* / Q000401:mortality / Q000635:transmission*; D007558:Italy / Q000453:epidemiology; D008962:Models, Theoretical; D058873:Pandemics; D012621:Seasons