According to the CDC, vaccination lasts 3-5 years, with protection waning after that. How fast the protection decreases is not entirely clear, especially on the scale of decades, but I did find this Scientific American article claiming that mortality rates were reduced from 52% among the unvaccinated to 1.5% for those vaccinated within ten years and to 11.5% for those vaccinated between 10 and 20 years prior in a study. This article suggests that vaccination during infancy reduced the mortality rate to under 5% for 30 years, and the mortality rate for vaccinated individuals was never above half that for unvaccinated individuals of the same age range. Similarly, mild cases of smallpox are far more common among infected vaccinated individuals than unvaccinated individuals. All this is to suggest that vaccination confers some kind of lifelong protection, at least statistically.
As for the difficulty, I would like to emphasize that this was very easy for me to do. Getting the appointment and vaccine took about 2 hours, and they were completely free. The swelling was a tad annoying but not too bad.
According to the CDC, vaccination lasts 3-5 years, with protection waning after that. How fast the protection decreases is not entirely clear, especially on the scale of decades, but I did find this Scientific American article claiming that mortality rates were reduced from 52% among the unvaccinated to 1.5% for those vaccinated within ten years and to 11.5% for those vaccinated between 10 and 20 years prior in a study. This article suggests that vaccination during infancy reduced the mortality rate to under 5% for 30 years, and the mortality rate for vaccinated individuals was never above half that for unvaccinated individuals of the same age range. Similarly, mild cases of smallpox are far more common among infected vaccinated individuals than unvaccinated individuals. All this is to suggest that vaccination confers some kind of lifelong protection, at least statistically.
As for the difficulty, I would like to emphasize that this was very easy for me to do. Getting the appointment and vaccine took about 2 hours, and they were completely free. The swelling was a tad annoying but not too bad.