I am pretty sure that it would be illegal to give people a vaccine designed to induce gene therapy that suppresses your immune system in order to ensure people need to get it more than once. And still, I actually trust the pharmaceutical companies to not do this more than I trust governments to not give them permission to do it, as they have been much better actors in the pandemic than almost every government.
Is it? We had immunosuppressors for decades, we know about about AIDS and gene therapy. Doesn't sound like such an extreme feat to me.