Seasonal Variations and Time Trends of COVID-19 Deaths Data in Italy: September 2021 Through September 2024, with Confirmation from Recent 2025 Updates

A previous research was conducted with the time series data of COVID-19 deaths in Italy in the period late September 2021- late September 2024. At that time, the epidemiological scenario was predominantly shaped by Omicron and its emerging sub-variants. In those earlier works, key findings revealed rising mortality trends in both winters and summers, with a more pronounced increase during winter. In particular, weekly COVID-19 deaths showed pronounced seasonal increasing variations of COVID-19 mortality, rising in summer and late fall to peak in early winter, and then declining in the late winter and spring periods. Using a linear regression model, a more recent investigation has validated the seasonal mortality pattern mentioned before. With recent data from 53 weeks starting with the end of May 2024 until the end of May 2025, we observed a repeating seasonal mortality pattern of COVID-19 deaths, rising in early summer and peaking in late fall. We then saw a steady decrease in COVID-19 mortality, mirroring the 2023–2024 trend, beginning in mid-winter and continuing until almost late spring. The study, supported by recent data, confirms that the COVID-19 mortality trend observed in previous years is still continuing, influenced by several factors that need further investigation