Vaccine passports aren't remotely a new concept. They date back to 1933 when the International Sanitary Convention for Aerial Navigation was signed at the Hague. The precusor to the Yellow Card of the World Health Organization. Prior to that there was a convention on maritime travel in 1926. The very first international convention on the matter began in 1851 after a large cholera outbreak to determine international guidance on quarantines.
With the rise in air travel and more understanding on infectious disease spread and mass vaccination, there was a general understanding it was in everyone's best interest to have certain vaccines be pushed for international travelers that were particularly high risk. The belief that the least intrusive means of mitigation would ensure the maximum amount of international travel. The first ones were for Cholera, Yellow Fever, Typhoid, and Smallpox. We now have them for Yellow Fever and Polio.
The Yellow Card was considered a key part of the successful elimination of Smallpox.
All the latest freakouts about Covid mitigations reveal a deep ignorance of the history of infectious disease control. A history that was significantly more brutal and more restrictive than the present.
"Banning me from your store for not wearing a mask is Nazism!"
"OK, just bring us proof that you're vaccinated and you can come in."
"No, that's Nazism too!"
"Holy shit, that guy over there just said he doesn't believe the Holocaust happened, what a Nazi!"
"What do you mean? He's just asking questions."