So how will Denmark s Covid-19 passport work?
At least four ready-made solutions exist based broadly on two types of technology. One relies on remote cloud servers where information is stored in bulk. The other uses blockchain, a more complicated system that could be better at protecting privacy.
Since personal medical data is so sensitive, it s a tricky decision. That s why many European nations covered by stringent EU privacy laws appear desperate for someone else to go first.
Digital toolbox
Ida Marie Odgaard/Ritzau Scanpix/AFP/Getty Images
The high level of investment in developing Covid passport systems indicates high private sector optimism that they will become a common way to open borders.