A bit of an aside, but I suppose relevant, 'science' portrays itself as factual but really it's only educated guesses.
That is completely and utterly untrue. If you want to be pedantic about it, nothing whatsoever can really be considered "factual". It's not 100% "factual" that the sun exists & supplies us with solar energy (in theory, it could be a figment of our collective imaginations) - but the likelihood that it's really there is so close to 100%, that it may as well be for all practical purposes.
So science simply cannot proclaim anything as a "fact". But that most certainly does not mean it only amounts to "educated guesses" - and I find that viewpoint really rather ignorant. Are you not familiar with the notion of evidence, data, research, the scientific method?
I don't doubt that parents who refuse to vaccinate feel they are doing the best for their children - but their doubts about the safeness of MMR are based entirely on nonsense & misinformation. Interestingly, people on here have written about reading reports that suggest MMR is not safe. I say interesting because no such scientific reports exist. All studies that have been done have shown over & over & over & over that MMR is safe, and there is no link to autism & Crohn's disease.
I suspect what they're reading are not the reports themselves, but the interpretations of them by unqualified hacks in the Daily Mail like Melanie Phillips.
The only people who can justify not vaccinating their children are those where it's medically contraindicated - and those children are very, very much in the minority.