> The whole principle that you need to prove vaccination to be let into a country is not really new.
Exactly. Necessary and recommended vaccinations are one of the first things to check when planning a trip to destinations in Africa, South East Asia etc.
This is true in the U.S. as well [0]. Some states allow for religious, philosophical, or medical exemptions; these exceptions are similar to the systems implemented in the Netherlands (religious [1]), Australia (philosophical [2]) or Germany (medical [1]).
