Your smallpox vaccine is likely useless by now.
Correct - one of the interesting reports from the world of medicine prior to COVID-19 was that while it had been believed that the smallpox vaccine conferred lifetime protection, enough people were now living long enough that it became clear that it didn’t. The mean point where a booster would have been required had not yet been determined at the time the COVID-19 panic started.
In 1900, there was a smallpox outbreak in London. Mortality among unvaccinated cases was 30%.
For those living then who caught smallpox but who were vaccinated as infants, including those vaccinated in or before 1850, the mortality was 3%.