The 1918–1919 influenza pandemic in England and Wales: spatial patterns in transmissibility and mortality impact

Spatial variations in disease patterns of the 1918–1919 influenza pandemic remain poorly studied. We explored the association between influenza death rates, transmissibility and several geographical and demographic indicators for the autumn and winter waves of the 1918–1919 pandemic in cities, towns and rural areas of England and Wales. Average measures of transmissibility, estimated by the reproduction number, ranged between 1.3 and 1.9, depending on model assumptions and pandemic wave and showed little spatial variation. Death rates varied markedly with urbanization, with 30–40% higher rates in cities and towns compared with rural areas. In addition, death rates varied with population size across rural settings, where low population areas fared worse. By contrast, we found no association between transmissibility, death rates and indicators of population density and residential crowding. Further studies of the geographical mortality patterns associated with the 1918–1919 influenza pandemic may be useful for pandemic planning.

References:

• G. Chowell, H. Nishiura. Quantifying the transmission potential of pandemic influenza. Physics of Life Reviews, doi:10.1016/j.plrev.2007.12.001 (pdf)
• G. Chowell, L.M.A. Bettencourt, N. Johnson, W.J. Alonso, C. Viboud.The 1918-1919 influenza pandemic in England and Wales: Spatial patterns in transmissibility and mortality impact. Proc. Roy. Soc. B, doi:10.1098/rspb.2007.1477 (pdf)
• H. Nishiura and G. Chowell. Household and community transmission of the Asian influenza A (H2N2) and influenza B viruses in 1957 and 1961. Southeast Asian J. Trop. Med. Pub. Health. 38(6), 1075-1083 (2007) (pdf)
• G. Chowell, C. E. Ammon, N. W. Hengartner, J. M. Hyman. Estimating the reproduction number from the initial phase of the Spanish flu pandemic waves in Geneva, Switzerland. Math Biosci Eng. 2007 Jul;4(3):457-70.(pdf)
• M. Nuno, G. Chowell, A. Gumel. Assessing the role of basic control measures, antivirals and vaccine in curtailing pandemic infuenza: Scenarios for the US, UK, and the Netherlands. J R Soc Interface 2007 Jun 22;4(14):505-21. (pdf)
• G. Chowell, C. E. Ammon, N. W. Hengartner, J. M. Hyman. Estimation of the Reproductive number of the Spanish Flu Epidemic in Geneva, Switzerland. Proceedings of the Second European Influenza Conference (St-Julians, Malta, September, 2005). Vaccine 24, 6747-6750 (2006) (pdf)
• G. Chowell, C. E. Ammon, N. W. Hengartner, J. M. Hyman. Transmission dynamics of the great influenza pandemic of 1918 in Geneva, Switzerland: Assessing the effects of hypothetical interventions. J. Theor. Biol. 241(2), 193-204 (2006) (pdf)
• T.L. Burr, G. Chowell. Observation and model error effects on parameter estimates in susceptible-infected-recovered epidemic model. Far East J. Theor. Stat. 19(2), 163-183 (2006) (pdf)
• G. Chowell, H. Nishiura, L.M.A. Bettencourt. Comparative estimation of the reproduction number for pandemic influenza from daily case notification data. J R Soc Interface 4, 155-166 (2007) (pdf)
• A.B. Gumel, M. Nuno, G. Chowell. Mathematical assessment of Canada's pandemic influenza preparedness plan. Can. J. Inf. Dis. & Med. Microb. (in press).

Figure 1. Weekly number of influenza-specific deaths during the 1918–1919 influenza pandemic in England and Wales at two different spatial scales: (a) 305 administrative units and (b) 62 counties (Ministry of Health 1920). The influenza mortality data cover 46 weeks comprising the week ending 29 June 1918 and continuing to the week ending 10 May 1919.

Figure 2. Timing of pandemic onset in the (a) autumn (1918) and (b) winter (1919) wave in the 305 administrative units of England andWales, as a function of population size. Q1–Q4 represent the quartiles of population size (Q1, lowest; Q4, highest).