Preliminary Programme

The 1918–20 pandemic of influenza is estimated to have killed between 50 and 100 million people worldwide. Previous research has shown that mortality varied between ethnic groups and geographical areas. In Norway, areas dominated by Sami people experienced 3–5 times higher mortality than the average of the country. We have for the first time analysed individual-level influenza mortality data 1918–20 by age and wave for two core areas of Norwegian Sapmi, Kautokeino and Karasjok. The age distribution of mortality has been examined based on a hypothesis that relative isolation and lack of previous exposure to seasonal influenza has resulted in higher mortality and a different age distribution of mortality than that typical of Spanish flu in non-isolated majority populations. Censuses and burial registers from church books are used to analyse age-specific all-cause excess mortality. An age-specific mortality pattern has been observed that differs from what is found in non-isolated populations with more mobility. The elderly had the highest mortality rate. It was not the young adults alone who produced the high excess mortality in Kautokeino and Karasjok. We hypothesize that a high degree of isolation and less prior immunity caused a higher mortality among the elderly and a different age-specific pattern. A distinct and previously unrecognized outbreak of the pandemic in Karasjok in 1920 is also documented. (Show less)

The U.S. territory of Alaska was one of the hardest hit regions of the world during the 1918 influenza pandemic, with some Native villages suffering up to 90% mortality. Overall, indigenous persons constituted nearly 80% of influenza deaths during the pandemic. Here we present results of a new assessment of pandemic impacts based on a collection of over 7000 death certificates dating between 1915 and 1921. Data on age, sex, indigeneity, date of death, cause of death, and place of death have been gleaned from these death certificates. Analyses focus on the excess mortality rates in both indigenous and non-indigenous groups, age- and sex-specific patterns of mortality in the two groups, and regional and temporal variation in pandemic incidence. Results confirm that Alaska experienced a very severe outbreak in 1918 and a more moderate outbreak in 1919, both of which disproportionately affected the indigenous population. Analyses also show, however, that there was a previously unrecognized peak in 1920. These three pandemic peaks all occurred in different parts of the territory. Analyses of qualitative historical materials collected at the Alaska State Archives provide possible explanations for the marked geographic structuring of the Alaska pandemic and its extreme severity in indigenous peoples. (Show less)

Most studies look at isolated pandemics, comparative studies are less frequent. In Switzerland, the research basis is particularly thin on past pandemics. Spatially comparative studies within Switzerland do not yet exist. One indicator of the overall impact of pandemics on a society is excess mortality, which follows the concept of expected value versus observed value. We make use of the fact that Switzerland has not changed territorially and that the data quality is excellent due to non-involvement in wars. The aim of the study is to calculate and partially explain excess mortality in the pandemic years 1890, 1918 and 2020 by district. We transcribed the number of all-cause deaths in the approximately 140 Swiss districts by age group and sex in the pandemic years 1890 and 1918 and the 4–5 years before from historical statistics by the federal authorities, along with population numbers. The same data for 2020 was provided by the Federal Statistical Office. Explanatory factors by district (for example GDP per capita, urbanisation, share of agricultural population, etc.) were taken either from scientific publication or from historical statistics. We apply a Bayesian approach in hierarchical modelling (INLA). In each of the three pandemics, there were specific regional clusters of districts with increased excess mortality according to age group and sex. The explanatory factors at the ecological level could partially suggest explanations for the patterns. In 1918, excess mortality was considerably higher than in the other two pandemic years 1890 and 2020. There are some similarities between the pandemics as a whole, but also important differences. (Show less)