Seems like an optimization of the age-old practice of refusing entry of people into countries who are unable to prove they are vaccinated against common illness

Seems like an optimization of the age-old practice of refusing entry of people into countries who are unable to prove they are vaccinated against common illness. When I travel in for example Africa and South America and Asia I bring my yellow vaccination card together with my passport, and this information is used to make entry decisions when I'm at the border of these countries. I'm not particularly upset at what Spain is doing here. We live in a society where people can travel freely within the European Union (Schengen). If you refuse to be part of societal obligations to combat a dangerous disease, then you shouldn't be upset if your traveling or interactions with other nation states will be impacted in one shape or another.