Danish football fans walk to stadiums with a coronavirus pass. © JumpStory

Danish football fans could already test an innovation yesterday. Fans of the most popular sport have the opportunity to visit arenas again, but only after meeting one condition. Fans must carry a COVID passport - a virtual app on a mobile device that shows whether a person has been vaccinated against the disease, whether their test result was negative in the last 72 hours, or whether they had COVID-19 in the last 2-12 weeks. It is also envisaged that in some cases this passport can be paper-based. The European Union aims for all its member states to use such a passport starting in June.