Climate warming and influenza dynamics: the modulating effects of seasonal temperature increases on epidemic patterns

The underexplored impact of climate change on influenza outbreak severity and duration hampers our understanding of how climate-driven changes affect transmission dynamics. Our study employs the SIRS (Susceptible-Infectious-Recovered-Susceptible) model to simulate incremental temperature rises (2.5 °C, 5 °C, 7.5 °C, and 10 °C) in winter and summer. Results show warming significantly influences infections across seasonal, interannual, and decadal scales. Higher temperatures significantly impact infection rates, especially in autumn and winter, with long-lasting effects extending 5-6 years. Sustained warming lowers the total infection numbers compared to pre-warming levels. When winter and summer experience simultaneous warming, infection fluctuations during the warming period are mainly driven by winter warming. Winter warming also lowers the peak-to-trough infection ratio, reducing epidemic intensity fluctuations. Additionally, parameter choices can significantly affect the impact of warming on infection rates. Warming of varying intensity and duration can significantly impact influenza outbreaks, potentially altering their seasonal patterns in a global warming context.