They'll respond to this by saying "yea, that's expected; the vaccine doesn't reduce case counts, it's reduced hospitalizations and deaths."

But when you argue that people being unvaccinated then only pose a risk to themselves, they'll argue that unvaccinated people lead to increased spread because the virus lives longer inside of them and there is more of it, and thus has more time and ability to spread to to others.

But they don't grasp that if that were true, then more vaccinated populations would show fewer cases, because even though each individual person vaxxed or unvaxxed is just as likely to contract it, each vaxxed person is less likely to transmit it.

The argument to be made here isn't that the vaccine is ineffective. The argument to be made here is that unvaccinated people are no more likely to transmit COVID-19 than vaccinated people.