I have a good friend, smart, well educated, professional guy. Left wing. His baby niece received her vaccinations. It was later discovered that she had a number of serious health conditions. She lived for a few extremely difficult years before sadly passing away just before COVID.
He became convinced that vaccines were responsible for everything and developed a deep-seated mistrust of mainstream medical advice. The pandemic was obviously very difficult for him. He was never combative with it, but he would occasionally share anti-vax stuff on social media, or get into long debates.
It was heartbreaking, because you could see that it came from a place of genuine good intentions; he just didn't want anyone else to suffer the pain that his family had been through, and he couldn't fathom why people were dismissing him or treating him like a nutter. In his mind, he wasn't some terminally online weirdo who'd 'done his research' on YouTube; he was a guy it had actually happened to.
I'm so opposed to anti-vax, we agreed never to discuss it for the sake of our friendship. But I totally and completely understand how his experience put him on that path, and I don't think less of him for it.
The social media anti-vax movement though, I treat with total distain. I have a pretty wide international circle on my SM due to work, hobbies, friends and family. Across such a broad spectrum, it was only ever the thickest, most uneducated, unsuccessful people I knew peddling it, and they were all selling the exact same lies.
I don't believe in coincidences of that size.