There are other vaccines such as the polio (the one which was swallowed) which had a similar mechanism. You could even infect others with it (which has benefits

There are other vaccines such as the polio (the one which was swallowed) which had a similar mechanism. You could even infect others with it (which has benefits for herd immunity). But the chances of vaccine-associated paralytic poliomyelitis was extremely low 1:2.700.000 (it was not given to people with immunity defects).