Abstract
Titrating the importance of endogenous and exogenous drivers for host-pathogen systems remains an important research frontier towards predicting future outbreaks. In Japan, respiratory syncytial virus (RSV), a major childhood respiratory pathogen, displayed a sudden, dramatic shift in outbreak seasonality (from winter to fall) in 2016. We use mathematical models to identify processes that could lead to this outcome. In line with previous analyses, we identify a robust quadratic relationship between transmission against mean specific humidity and mean temperature, with maximum transmission occurring at low and high humidity as well as low and high temperature. This drives semiannual patterns of seasonal transmission rates that peak in summer and winter. Under this transmission regime, a subtle increase in population-level susceptibility or transmission can cause a sudden shift in seasonality, where the degree of shift is primarily determined by the interval between the two peaks of seasonal transmission rate. We hypothesize that an increase in children attending childcare facilities may have contributed to the increase in the overall RSV transmission through increased contact rates between susceptible and infected hosts. Our analysis underscores the power of studying infectious disease dynamics to titrate the roles of underlying drivers of dynamical transitions in ecology.
Data availability
All data are stored in a publicly available GitHub repository (https://github.com/parksw3/perturbation)53.
Code availability
All code are stored in a publicly available GitHub repository (https://github.com/parksw3/perturbation)53.
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Acknowledgements
We acknowledge the efforts of the National Institute of Infectious Diseases, Statistics Bureau of Japan, and Children and Families Agency for collecting/maintaining the data used in this study and making them publicly available. E.H., B.T.G., and C.J.E.M. have been funded in whole or in part with Federal funds from the National Cancer Institute, National Institutes of Health, under Prime Contract No. 75N91019D00024, Task Order No. 75N91023F00016. The content of this publication does not necessarily reflect the views or policies of the National Institutes of Health or the Department of Health and Human Services, nor does mention of trade names, commercial products or organizations imply endorsement by the U.S. Government. S.W.P. acknowledges support from Peter and Carmen Lucia Buck Foundation Awardee of the Life Sciences Research Foundation and the New Faculty Startup Fund from Seoul National University. I.H. received postdoctoral funding from the High Meadows Environmental Institute of Princeton University. B.T.G. and C.J.E.M. acknowledge support from Princeton Catalysis Initiative and Princeton Precision Health. S.C. is supported by Federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services under CEIRR contract 75N93021C00015—Subcontract 77789. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIAID or the National Institutes of Health.
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S.W.P., I.H., and B.T.G. conceived of the study. S.W.P. performed the analysis and wrote the initial draft. All authors (S.W.P., I.H., E.H., W.Y., R.E.B., G.A.V., S.C., C.J.E.M., and B.T.G.) reviewed and edited the manuscript.
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Park, S.W., Holmdahl, I., Howerton, E. et al. Interplay between climate and childhood mixing can explain a sudden shift in RSV seasonality in Japan.
Nat Commun (2025). https://doi.org/10.1038/s41467-025-66184-y
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DOI: https://doi.org/10.1038/s41467-025-66184-y
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