Differences in the Clinical Course of COVID-19 in Patients Hospitalized in the 2023/2024 and 2024/2025 Seasons

Background/Objectives: The aim of this analysis of data from the multi-year nationwide SARSTer program in Poland was to compare the clinical presentation and course of COVID-19 in the last two infectious seasons. Methods: Clinical data from 719 consecutive patients hospitalized between April 2023 and March 2024 were compared with data from 360 patients hospitalized between 1 April 2024 and 31 March 2025. Results: In the 2023/2024 season, hospitalizations due to COVID-19 occurred primarily between September and January, and in the 2024/2025 season, the majority of hospitalizations occurred between July and November. In the 2024/2025 season, we documented a change in the age structure, with an increasing predominance of hospitalized patients over 70 years of age (68% vs. 60% in 2023/2024), a milder disease manifestation, reflected in a significantly lower percentage of patients with pulmonary lesions (19% vs. 24%), an improvement in the clinical course of the disease, reflected in a halving of the number of hospitalizations, a significantly higher percentage of patients with clinical improvement in subsequent weeks of hospitalization, including those discharged from the hospital within the first week (39% vs. 30%), and a significantly lower mortality rate (4.7% vs. 7.9%), especially among patients over 70 years of age (5.4% vs. 10.4%). This indicates that the trend of a milder disease course initiated by the emergence of the Omicron variant continues. Conclusions: In conclusion, our findings provide real-world clinical evidence of the evolution of the COVID-19 situation in the post-pandemic era.