[pekk]

Being vaccinated does not ALWAYS mean that you are individually immune, even if it is a lot better than not getting any vaccinations.

Many vaccines build "herd immunity" and will not work as well if people decide to opt out for some frivolous reason.

Also of course some people cannot receive a specific vaccine because they are pregnant or immunocompromised. Others should be vaccinated to prevent spread to those vulnerable populations, not just to protect themselves.