Just as with anything else, unless or until they're willing to change, they won't. There's absolutely nothing one can do to change someone else unless the other person is willing to be a part of that change and wants to change.
Keep loving them and guide them if they ask questions. If they aren't asking questions, the time to speak to them isn't right.
anon's spidey senses perked up at this post. Willing to share more? Anon is interested.
Keep in mind too that cognitive dissonance is a real thing. Mark Twain told us it was easier to fool someone than it is to convince them they've been fooled.
Imagine facing the fact that you chose to inject yourself with truly toxic sludge that may very well be killing you. It would be easy to go full ostrich and ignore the issue.
That might be why there's little response. Maybe their own research is showing them they're doomed.
Another possibility to reach them: present info on emerging treatments for myocarditis, for blood poisoning, show the ivermectin, fenbendazole, and hydroxychloroquine regimens that are helping millions around the world.
They might not be open to "being wrong" but I've found few who would turn down interesting and new medical information that might save their lives.
The last quote that really spoke to me about this is the following: "Nobody cares how much you know until they know how much you care."
Could always try it. Boron yields interesting results when researched via NIH.
What's the deal with tonic water anon?