Pandemic revisited: Characteristics, severity and clinical outcomes of patients hospitalized with SARS-CoV-2-infection in different periods of the pandemic.

The SARS-CoV-2-pandemic changed considerably over the course of time in terms of severity and mortality due to the impact of several SARS-CoV-2 variants as well as vaccination and preventive or SARS-CoV-2 specific therapies. We compared patients in two defined periods and analyzed the specific impact of pneumonia, including measures for treatment of respiratory failure.This was a single-center retrospective study of patients hospitalized with PCR-confirmed and symptomatic SARS-CoV-2-infection in our center. The pandemic periods 3/2020-12/2021 and 1/2022-3/2023 as well as the periods after establishment of vaccination, preventive and SARS-CoV-2-specific treatments 3/2020-9/2021 and 10/2021-3/2023 were compared.Overall, n=622 patients were included (n=307 in the first and n=315 in the second pandemic period). Marked differences were found with regard to age, severity of disease and pneumonia, interventions and mortality. Mortality of pneumonia was 25% (27% in the first and 20% in the second pandemic period); 40% of patients (36% patients with pneumonia) who died had not been admitted previously to the ICU. Mortality from pneumonia after exclusion of these patients was 18% (21% in the first and 10% in the second period). Mortality was particularly high in intubated patients with mechanical ventilation (67%).Our results were comparable with those reported in a national survey and another single center report of a nearby hospital. Treatment restrictions were frequently applied. Risk factors, severity and mortality of SARS-CoV-2-associated pneumonia in the second pandemic period were similar to those reported for community-acquired pneumonia. Excess mortality from mechanical ventilation deserves further investigation.