Don't tell the anti-vaxxers how dangerous the smallpox vaccine was. There was a reason why everyone wanted to stop giving smallpox vaccinations as soon as possible.Smallpox is the other disease which comes to mind when I think of effective, worldwide vaccination programmes.
A damn sight better than smallpox, though.
Among facts that might upset anti-vaxxers: the truth about the relative risks of covid-19 & other vaccines. They seem to think covid-19 vaccines (or "the vaccine", as they call them) are more, not less, dangerous than traditional vaccines. Doh!