CORFU joins 7 existing cohort studies to document persistent symptoms and quality of life (QoL) following COVID-19 infection, explores pathophysiological pathways, and develops a prognostic model to predict the probability of persistence (chronicity) of complaints. Post-COVID patients, from those at home to those admitted to the ICU, and additional healthy controls, will be approached at fixed time points after first infection (3m, 6m, 12m, 24m) to respond to a digital survey. The core survey consists of modules on symptoms, QoL,social relations, participation and psychological function. Workpackage (WP) 1 describes the incidence of symptoms/complaints and patterns thereof, and QOL over time,and the care received, including informal and self-care. We will identify phenotypes of persistent symptoms/complaints. WP2 analyses pathophysiology of persistent complaints using published evidence/pre-existing knowledge and hypotheses, incl the phenotypes of WP 1. WP 3 develops a prediction model for persisting complaints. Predictors for chronicity of complaints will be selected from the literature and WP1 and WP2. The cohorts will offer options to focus on predictions for their defining feature. WP4 combines activities to harmonize the survey across cohorts, the digital data collection itself, with analysis (cost of illness). Additionally, WP4 configures (in 1 location) a patient information platform to inform patients individually on her/his own condition and prospect, relative to others.