Denmark use a similar app called “Coronapas”. Works similar to the Swiss one, displaying latest test results and vaccine status. It’s currently required to enter any restaurants or public spaces and has been very successful in returning some degree of normality to the country. Singapore are trialing a similar solution where the “Trace Together” app displays my vaccine status, possible exposure as well as test results. Very efficient. Different countries, different traditions. The US seems quite opposed to federally enforcing vaccine registration and passports, yet they find it ok to conduct mass surveillance of its citizens (and foreigners). On the contrary, Germany have strict privacy laws; yet they push for digital vaccine passports.