The spatial anatomy of an epidemic: influenza in London and the county boroughs of England and Wales, 1918–1919

Abstract

From uncertain origins in the spring of 1918, an apparently new variant of influenza A virus spread around the world as three distinct diffusion waves, infecting half a billion and probably killing around 40 million people. This paper examines the spatial structure of influenza transmission during the ten-month course of the epidemic in England and Wales, June 1918-April 1919, using the weekly counts of influenza deaths in London and the county boroughs as collated by the General Register Office, London. In addition, a particular case study of the borough of Cambridge is presented. From mid-1916, Cambridge contained, as well as its undergraduate population, a large naval contingent billeted in both the colleges and the town. It therefore affords the opportunity of studying the effect of the epidemic in contiguous groups with widely differing demographic characteristics. Through the application of a range of statistical methods (average lags, correlations and regressions), it is shown that the three waves that comprised the pandemic had fundamentally different spatial and temporal characteristics. The first, moving through a population that was a virgin soil to the new virus strain, was explosive in its north to south progress across the country. The second wave was somewhat slower in its rate of diffusion and displayed a south to north drift. Finally, the third wave reverted more closely to the form of the first. The spread of all three waves, however, was underpinned by a clearly defined process of spatial contagion. The Cambridge study showed the special characteristics of this pandemic in terms of the ages of those attacked: high rates were experienced across the age spectrum, a feature also seen internationally. key words influenza spatial diffusion England and Wales 1918-19

Disparities in influenza mortality and transmission related to sociodemographic factors within Chicago in the pandemic of 1918

“…Deaths were more likely to occur within the same week and a few hundred meters than expected given the underlying spatial and temporal clustering, speaking to the importance of neighborhood-level transmission even in a mobile, urban population. Previous studies found significant autocorrelation in influenza mortality across county boroughs in England and Wales (42) and provinces in Spain (20), but this study is unique in showing a spatial dependence in the spread of individual influenza cases during the 1918 pandemic.…”

Synchrony, Waves, and Spatial Hierarchies in the Spread of Influenza

“…The spatial spread of influenza has been much studied, particularly with respect to pandemic invasion waves (5)(6)(7)(8)(9)(10)(11). Simulation models incorporating air and surface transportation have generated important insights into the spread of influenza (6,7,10,11); however, the key underlying relationship between human movement and disease spread has not been verified across wide spatial scales nor contrasted among multiple interpandemic seasons of varying severity and viral subtype dominance.…”

The influence of changing host immunity on 1918–19 pandemic dynamics

“…Error bars for composite data points are calculated using bootstrapping methods (Efron, 1979). Our aggregation will average over spatial heterogeneities, which reflect the spatial diffusion of the pathogen (Smallman-Raynor et al, 2002;Eggo et al, 2010). However the cities that have symptom reporting data available are all located in mid-north England and have epidemics of similar timing.…”

“…Fraser et al, 2011;Valleron et al, 2010). However the ecological conditions which gave rise to the three distinct peaks of mortality over a period of just nine months in England and Wales (Smallman-Raynor et al, 2002;Pearce et al, 2011) remain intriguing.…”