Pathophysiology of the development of Acute Respiratory Distress Syndrome (ARDS) in the ongoing SARS-CoV2 pandemic is unknown. It is hypothesised that ARDS is driven by an locally over-reacting innate immune response. The complement system is a key-player of the innate immune system and has been shown to be involved in systemic inflammation and ARDS of other causes. Complement therapeutics inhibiting the complement system are clinically available. Here, we will measure complement system activation as a standard clinical marker in all COVID-19 patients admitted to Oslo University Hospital Ullevål and Rikshospitalet at one day and follow-up patient outcome at day 30 after analysis. Aim is to decide if a clinical study investigating complement inhibition has a rationale to be performed at Oslo University Hospital and the project is thus an internal quality registry.