Background: Since the start of the COVID-19 pandemic, novel SARS-CoV-2 variants of concern have emerged, some of which have become largely dominant including the B.1.1.7 (alpha), the B.1.617 (delta) and more recently the B.1.1.529 (omicron). The clinical implications of the different variants in unvaccinated and vaccinated persons are still not adequately characterized. The detailed understanding of the interplay between the variants, vaccine immune responses and disease severity is still scarce.~Study objectives:~Overall objectives are:~to collect data and/or biological material from COVID-19 in-patients in a diverse setting of 12 clinics in 11 countries and 4 continents~to analyse the clinical course of COVID-19 in in-patients in relation to the viral characteristics~to analyse the clinical course of COVID-19 in in-patients in relation to vaccines used and vaccination schedules~to deliver recommendations for optimized clinical management and treatment with special consideration to viral characteristics and to used vaccines~Specific objectives are:~To describe the patterns of clinical symptoms, therapeutic interventions and clinical outcome in patients hospitalized from 12 hospitals/clinics, in 11 countries and 4 continents.~To assess the impact of viral variants / viral sequences on the clinical outcome measured as all-cause in-hospital mortality, non-invasive mechanical ventilation/high-flow nasal oxygen, mechanical ventilation, admission to intensive care unit, length of time in intensive care and overall length of hospitalization.~To assess the impact of different vaccines and vaccination schedules on the clinical outcome measured as all-cause in-hospital mortality, non-invasive mechanical ventilation/high-flow nasal oxygen, mechanical ventilation, admission to intensive care unit, length of time in intensive care and overall length of hospitalization.~To assess the impact of viral variants / sequences in response to treatment interventions and the associated clinical outcome~To assess the impact of different vaccines and vaccination schedules in response to treatment interventions and the associated clinical outcome~To provide WP2 in EuCARE with biological material for further studies on viral characteristics and associated immune responses~To provide WP5 in EuCARE with data for further studies using artificial intelligence
The WP3 hospitalized cohort in EuCARE is an observational multicentre study including collection of retrospective (historical) and prospective data from hospitalized COVID-19 patients followed at 12 clinics from 11 countries from 4 continents. In a subset of patients, peripheral blood, viral isolates and/or viral sequences are collected for analysis in WP2 with regards to neutralising antibodies, cellular immunity and SARS-CoV-2 diagnostics. Data and results from analysis of biological material will be analysed by biostatistical methods and with artificial intelligence in WP5. This analysis will focus on the impact on clinical outcome of viral variants / viral sequences as well as the vaccines used and the vaccination schedules.