The transmissibility of influenza pandemics. The case of 1889-1890 and 1918-1920 in a large urban environment: a spatial analysis of Madrid, Spain, by borough and district

Diego Ramiro-Fariñas, Consejo Superior de Investigaciones Científicas (CSIC)
Yolanda Casado, Consejo Superior de Investigaciones Científicas (CSIC)
Sara García Ferrero, Consejo Superior de Investigaciones Científicas (CSIC)

The 1918–1919 pandemic influenza, the “Spanish” flu, killed about 50 million people worldwide. There have been many studies of the transmissibility of the 1918 Spanish flu virus. Many analyses have involved fitting transmission models to the observed epidemic curves based on published data from cities in Europe or America. These attempts to estimate the rate of transmissibility of influenza among people have the objective of planning mitigation strategies and control of infectious diseases from potential new pandemics. Quite often these estimations relays on historical published data from where parameters that model the transmission of the disease are estimated. Other pandemics, like the influenza pandemic during the winter of 1889-1890, the "Russian Flu", was one of the most important pandemics during the XIXth century and it was the first influenza pandemic in an interconnected world. The transmissibility rate for the 1889-1890 pandemic in Europe was estimated to be R0=2.1. While the transmissibility rate of the 1918-1919 pandemic was estimated approximately to be R0=2 and 3 for 45 cities in the United States. Therefore, the estimation of this parameter and the patterns of geographical distribution within a big urban environment are of great interest because it will allow determining the potential diffusion of an epidemic and how that epidemic could be tackled and controlled. Therefore, the scientific goal of this contribution is to estimate transmissibility rates and the geographical distribution of two influenza pandemics 1889-1890 and 1918-1920 in the boroughs and districts of the City of Madrid, which had a population around 500.000 inhabitants in 1900 and c700.000 in 1920. We will use the Longitudinal Historical Population Register of the City of Madrid which uses individual level information for all the individuals who lived and died in Madrid.