Respiratory
Evaluating climate drivers of influenza dynamics across tropical and temperate regions Aleksandra Stamper* Aleksandra Stamper Rachel Baker
Influenza infections contribute significantly to global morbidity and mortality each year. Climate plays a critical role in shaping influenza outbreaks, with distinct patterns observed across regions. In temperate areas, influenza epidemics typically occur in the wintertime, while tropical regions exhibit more persistent influenza activity throughout the year with less defined outbreak peaks. Specific humidity, a measure of water vapor per volume of air, has been identified as a key climate driver of influenza dynamics in temperate regions, where lower levels of specific humidity are associated with higher transmission rates. In tropical regions, influenza transmission occurs in both cold, low-specific humidity and hot, high-specific humidity conditions.
Epidemiological compartmental models provide a valuable tool for investigating relationships between climate and influenza activity. However, existing models are often tailored to specific climatic regions, and no universally validated model currently exists to account for influenza dynamics across a wide range of weather conditions. Using an epidemiological model fit to historic climate and influenza data, we explore whether a common set of climate drivers can explain influenza dynamics across diverse climates.
We adapted the Susceptible-Infected-Recovered model, applying it to data from a northern hemisphere temperate location (Michigan, United States), a southern hemisphere temperate location (Paraná, Brazil), and a tropical location (Nicaragua). The model was fit to historic weekly influenza and climate data. By calculating the predicted reproduction number for various combinations of climate factors, we map the nonlinear relationship between specific humidity, temperature, and influenza transmission. The framework developed here offers insight into the feasibility of a universal influenza model, which could play a crucial role in assessing the potential impacts of climate change on future influenza outbreaks.