Jérémie Boudreault, Sophie Calcaneo, Félix Lamothe, Eric Lavigne, Céline Campagna, Fateh Chebana
Abstract Suboptimal temperatures are becoming a major cause of mortality worldwide. However, the recent changes in temperature-related mortality burden due to the COVID-19 pandemic remain unclear, with only a few studies conducted in Europe and Asia reporting diverging results. This study aims to estimate the heat-related and cold-related mortality burden between 2000 and 2024 in the context of the COVID-19 pandemic in a North American context. Using data from the province of Quebec, Canada, we estimated temperature-mortality functions with distributed lag non-linear models and multivariate meta-regression. Models were developed including or excluding COVID-19 deaths and years, as well as separately for the summer season (May to September), the winter season (November to March) and for the whole year. Mortality attributable to moderate, extreme and total heat and cold was calculated using the different models. The total heat-related burden was estimated at 375 and 550 deaths per year using respectively the summer and the annual models. A non-significant reduction of ∼100 heat-related deaths per year was noted when including COVID-19 years in the analysis compared to the pre-COVID-19 period. The cold-related burden was estimated at 850 and 4000 deaths per year using respectively the winter and the annual model. The cold burden was highly sensitive to the studied months and to models’ parameters. Excluding COVID-19 deaths decreased the cold-related mortality burden. These new results can help health authorities improve their temperature surveillance through a better understanding of the recent shifts due to the COVID-19 period. Heat surveillance should focus on both moderate and extreme hot temperatures, each representing half of the heat-related mortality burden, while cold surveillance should target moderate cold temperatures (i.e. 0° to −20 °C) that accounted for >90% of the cold burden.