The benefit of the attenuated live virus is that it can replicate and go on to infect others, spreading protection from virulent polio to unvaccinated people.

The benefit of the attenuated live virus is that it can replicate and go on to infect others, spreading protection from virulent polio to unvaccinated people. One of the covid-19 origin theories was that China was trying to make an attenuated live virus SARS vaccine that would self propagate through the population