Recurrent outbreaks of the avian H5N1 influenza virus in Asia represent a constant global pandemic threat. We characterize and evaluate hypothetical public health measures during the 1918 influenza pandemic in the Canton of Geneva, Switzerland. The transmission rate, the recovery rate, the diagnostic rate, the relative infectiousness of asymptomatic cases, and the proportion of clinical cases are estimated through least-squares fitting of the model to epidemic curve data of the cumulative number of hospital notifications. The latent period and the case fatality proportion are taken from published literature. We determine the variance and identifiability of model parameters via a simulation study. Our epidemic model agrees well with the observed epidemic data. We estimate the basic reproductive number for the spring wave R1^=1.49 (95% CI: 1.45–1.53) and the reproductive number for the fall wave R2^=3.75 (95% CI: 3.57–3.93). In addition, we estimate the clinical reporting for these two waves to be 59.7% (95% CI: 55.7–63.7) and 83% (95% CI: 79–87). We surmise that the lower reporting in the first wave can be explained by a lack of initial awareness of the epidemic and the relative higher severity of the symptoms experienced during the fall wave. We found that effective isolation measures in hospital clinics at best would only ensure control with probability 0.87 while reducing the transmission rate by >76.5% guarantees stopping an epidemic.

The 1918 influenza pandemic known as the "Spanish Flu" has been the worst in recent history with estimated worldwide mortality ranging from 20 to 100 million deaths. Using epidemic modeling and hospital notification data during the 1918 influenza pandemic in the Canton of Geneva, Switzerland, we estimated the reproductive numbers of the first and second waves of influenza infection to be R1 = 1.49 (95% CI: 1.45–1.53) and R2 = 3.75 (95% CI: 3.57–3.93), respectively. Our estimates indicate that containment of the next influenza pandemic could require strict interventions that include effective isolation strategies in hospitals and reductions in the susceptibility of the general population.

A Geneve (Suisse), l’epidemie de grippe espagnole de 1918 a touche plus de 50% de la population. La mortalite la plus elevee se trouvait dans le groupe des 20–49 ans et chez les hommes. L’impact socio-economique fut tres important, l’epidemie entrainant de graves disfonctionnements, y compris dans les services sanitaires. Cette epidemie majeure illustre l’impact socio-economique que peut avoir la grippe et souligne la necessite de se preparer a toute eventuelle pandemie.

En Ginebra, Suiza, la epidemia de gripe espanola afecto a mas del 50% de la poblacion. La mortalidad mas elevada tuvo lugar en personas de 20-49 anos de edad y en varones. El impacto socioeconomico fue muy importante, dado que la epidemia produjo trastornos graves, incluso en los servicios de salud. Esta epidemia muestra el impacto socioeconomico que puede acarrear la gripe y subraya la necesidad de la preparacion ante eventuales pandemias.