Abstract
Co-circulation of multiple influenza subtypes poses a major challenge to global public health. However, its specific impact on non-stationary epidemic sequences and coupling relationships with environmental drivers remains poorly understood. By integrating STL, Adaptive Fourier Decomposition, Continuous Wavelet Transform, and Wavelet Coherence, we analyzed 323 weekly influenza surveillance time series from China (2011–2025). The study identifies a fundamental regime shift during co-circulation periods, transitioning from ordered single-dominant transmission to a chaotic state. This instability is characterized by significant dominant periodicity dispersion, amplified seasonality shifts, and high-intensity anomalies in residual components, with overall seasonal strength dropping by 28%. Crucially, we uncover a marked north-south mechanistic divergence: northern regions exhibited “Environmental Locking,” remaining strongly constrained by climates during co-circulation; conversely, southern regions demonstrated “Environmental Decoupling” (H3N2 phase consistency with soil moisture plummeted from R=0.45 to 0.07), where viral ecological competition overshadowed environmental drivers. Influenza co-circulation acts as a systemic perturbation reshaping transmission dynamics. Our findings highlight the necessity for context-adaptive strategies: northern regions can maintain reliance on meteorological warnings, while southern regions must dynamically shift focus toward real-time virological surveillance during co-circulation to capture rapid ecological shifts.
Similar content being viewed by others
Characterization and forecast of global influenza subtype dynamics
Cross-reactive immunity potentially drives global oscillation and opposed alternation patterns of seasonal influenza A viruses
Disruption of seasonal influenza circulation and evolution during the 2009 H1N1 and COVID-19 pandemics in Southeastern Asia
Acknowledgements
This work was supported in part by the Science and Technology Development Fund of Macau SAR under Grants 0111/2023/AFJ and 0002/2024/RDP. We thank the staff of the China National Influenza Center and the researchers who contributed to the ERA5-Land and Baidu Index datasets for making their data publicly available.
Author information
Authors and Affiliations
Corresponding authors
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary information
Supplementary information (download PDF )
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
Reprints and permissions
About this article
Cite this article
Liu, H., Li, X., Sun, N. et al. Spatiotemporal instability of influenza seasonality during viral co-circulation.
npj Syst Biol Appl (2026). https://doi.org/10.1038/s41540-026-00729-9
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41540-026-00729-9
Source: Ecology - nature.com
