There isn’t one. We have never forced MMR we have never forced flu vaccines. You encourage take up not force. Democratic societies don’t force or then victimise those concerned about it
The choice is to take the vaccine or not. The argument needs to be won on the grounds of being right not manipulation and coercion. I’ve changed my mind now having seen the vitriol. Science and evidence wins not threats. It’s not about slippery slope it’s just wrong to coerce people to take vaccines. I may change my mind again if someone can show me facts about the issues the minority are causing
But in the past it's been easier to encourage take up because it wasn't as easy for the nutcases opposing it to interact with and influence millions of people almost immediately via the internet and being given as much publicity as those qualified to talk about it. Take this woman ranting in London. Beforehand such a thing would have never got much further than those few nutters listening in that park, and where it did it would spread slowly and be manageable. Now everyone around the country knows about it in the space of a few hours and it can cause far more widespread damage much more quickly
Now you've got that problem you've got to stamp down to stop these unfounded rumours and conspiracies, but that's going to take time. We don't have that time to deal with a healthcare emergency so you're going to have to use as much carrot and stick as you can to get people vaccinated. I think forcing people can be counter-productive and, in this society, will see people push back against authority because they don't like being told what to do. It just adds to the conspiracy theories because if they're forcing you what is it they're not telling you.
But even if you use a soft approach like offering incentives, tax breaks or even cash to get people on board it won't stop those theories. Again if anything adds fuel to the fire. A harder approach, such as telling people refusal of the vaccine will lead to restrictions on your ability to work, travel, recreation or at an extreme level refusal of treatment for Covid complications should they arise, would be the same but are seen as authoritarian, callous and uncaring.