Originally Posted by
drminn
It is actually worse than that, at least in theory. In Germany for example there are state specific rules, so when entering you have to follow the national rules and then the state rules. And to add insult to injury, things change frequently. In practice, nobody seems to care, i.e. ask for anything, when you enter the country. So what you need is really what Delta asks you to provide/ lets you get away with.
Once you are in the country, you need proof of vaccination to go to restaurants, museums, and to take a plane, maybe more. All kinds of proof are acceptable, the US CDC card works almost everywhere in Germany, in France they ask for QR code.
It's funny, Germany for most part will take CDC card, but makes it very easy for foreigners to get EU version. France requires the EU version, but makes you jump through couple hoops and wait forever to get one (if they don't just outright cancel request).