When people want the truth, they'll find it. If they don't want it, no amount of effort will guide them to it.

Don't guide them with facts. Guide them to seek the truth. There's a reason they're avoiding truth. Fix that.

In my case, what works is asking them to seek God for advice. If they die from someone's bad advice, then the angels will ask them why they chose to follow that advice when their hearts told them otherwise. If they follow God's advice and died, then it's just their time and they'd be judged as martyrs for following it.

Everyone I've said that to later took the vaccine. It doesn't have to be religious, but appeal to their highest morality, not yours.