High-resolution influenza mapping of a city reveals socioeconomic determinants of transmission within and between urban quarters

Egli, Adrian; Goldman, Nina; Müller, Nicola F.; Brunner, Myrta; Wüthrich, Daniel; Tschudin-Sutter, Sarah; Hodcroft, Emma; Neher, Richard; Saalfrank, Claudia; Hadfield, James; Bedford, Trevor; Syedbasha, Mohammedyaseen; Vogel, Thomas; Augustin, Noémie; Bauer, Jan; Sailer, Nadine; Amar-Sliwa, Nadezhda; Lang, Daniela; Seth-Smith, Helena M.B.; Blaich, Annette; Hollenstein, Yvonne; Dubuis, Olivier; Nägele, Michael; Buser, Andreas; Nickel, Christian H.; Ritz, Nicole; Zeller, Andreas; Stadler, Tanja; Battegay, Manuel; Schneider-Sliwa, Rita

With two-thirds of the global population projected to be living in urban areas by 2050, understanding the transmission patterns of viral pathogens within cities is crucial for effective prevention strategies. Here, in unprecedented spatial resolution, we analysed the socioeconomic determinants of influenza transmission in a European city. We combined geographical and epidemiological data with whole genome sequencing of influenza viruses at the scale of urban quarters and statistical blocks, the smallest geographic subdivisions within a city. We observed annually re-occurring geographic clusters of influenza incidences, mainly associated with net income, and independent of population density and living space. Vaccination against influenza was also mainly associated with household income and was linked to the likelihood of influenza-like illness within an urban quarter. Transmissions patterns within and between quarters were complex. High-resolution city-level epidemiological studies combined with social science surveys such as this will be essential for understanding seasonal and pandemic transmission chains and delivering tailored public health information and vaccination programs at the municipal level.