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Data from: Seasonality in the migration and establishment of H3N2 Influenza lineages with epidemic growth and decline


Zinder, Daniel et al. (2014), Data from: Seasonality in the migration and establishment of H3N2 Influenza lineages with epidemic growth and decline, Dryad, Dataset,


Background: Influenza A/H3N2 has been circulating in humans since 1968, causing considerable morbidity and mortality. Although H3N2 incidence is highly seasonal, how such seasonality contributes to global phylogeographic migration dynamics has not yet been established. In this study, we incorporate time-varying migration rates in a Bayesian MCMC framework. We focus on migration within China and between China and North-America as case studies, then expand the analysis to global communities. Results: Incorporating seasonally varying migration rates improves the modeling of migration in our case studies, and of global influenza population dynamics. In our global model, windows of increased immigration (in migration) map to the seasonal timing of epidemic spread, while windows of increased emigration (out migration) map to epidemic decline. Seasonal patterns also correlate with the probability that local lineages go extinct and fail to contribute to long term viral evolution, as measured through the trunk of the phylogeny. However, the fraction of the trunk in each community was found to be better determined by its overall human population size. Conclusions: Seasonal migration and rapid turnover within regions is sustained by the invasion of 'fertile epidemic grounds' at the end of older epidemics. Thus, the current emphasis on connectivity, including air-travel, should be complemented with a better understanding of the conditions and timing required for successful establishment. This will better our understanding of the seasonal drivers of influenza, improve epidemiological predictions, and improve vaccine updating by identifying strains that not only escape immunity but also have the seasonal opportunity to establish and spread, identified through models which account for migration seasonality. Further work is also needed on additional conditions that contribute to the persistence and long term evolution of influenza within the human population, such as spatial heterogeneity with respect to climate and seasonality.

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