Meteorological drivers of seasonality of acute respiratory viral infections in the Czech Republic

Abstract In temperate climates, acute respiratory viral infections (ARIs), including influenza, respiratory syncytial virus, parainfluenza virus, and human metapneumovirus, represent a major burden to public health, particularly during the winter half-year. These viruses display strong and recurring seasonal patterns, yet the underlying environmental drivers of their transmission dynamics remain only partially understood. As climate change is expected to alter temperature and humidity regimes in temperate regions, a deeper understanding of the relationships between weather conditions and ARI activity is increasingly needed. This study analyses the seasonality and meteorological response of selected respiratory viruses in the Czech Republic using weekly incidence data from the 2011/12 to the 2023/24 epidemic seasons. Additionally, influenza-like illness data are incorporated to complement virus-specific patterns. Meteorological parameters include air temperature, relative and absolute humidity, and sunshine duration. Quasi-Poisson regression models with a distributed lag non-linear framework are applied to quantify seasonal and short-term associations between the relative risk of incidence of selected ARI and weather variables. First results show that air temperature, followed by absolute humidity, is the primary weather factor linked to influenza, with severe outbreaks occurring after prolonged cold periods, whereas milder outbreaks are associated with warmer conditions. Further research will be conducted to analyse the ARI seasonality and the combined effects of weather variables. The findings are expected to improve forecasting of respiratory virus activity, inform public health preparedness strategies, and support the development of early warning systems. In light of projected climatic change, such knowledge is essential for anticipating changes in disease seasonality and mitigating the health impacts of respiratory infections in a warming world. Key messages • Seasonal patterns of respiratory viruses such as influenza and RSV are closely linked to weather conditions, particularly temperature and humidity. • Understanding how meteorological factors influence ARI dynamics is essential for anticipating future shifts in seasonality and improving public health responses in the context of climate change.