That leaves the parents who couldn't help noticing that their child who had been alert and active stopped being alert and active right after, or soon after, being vaccinated.
The son of friends of mine was diagnosed as autistic, following them noticing symptoms which manifested themselves shortly after his MMR jab. His mother was convinced that the jab caused his autism (she's less convinced now, but more of that later). The point is that the correlation of his symptoms, and recently receiving the jab, is, I would agree, certainly a very good reason to ask the question whether the MMR jab causes, triggers, or contributes to autism. Fair enough on that one - the question should definitely be asked.
And asked it was. Scientists were asked, many times, and after a large amount of research, and a couple of false leads, the answer was arrived at that the research shows that there is no cause and effect between the MMR jab and autism. It's simply correlation.
The thing is, the symptoms of autism tend to become noticeable at around the stage that children tend to receive the vaccination. My stepson-to-be is strongly autistic, and although I only met my fiance after his diagnosis, I have watched videos of him when younger, and spoken with her at length about it. An autistic baby behaves the same as a non-autistic one (or certainly within the range of non-autistic behaviour at that age) - you start to get an inkling that something isn't quite usual somewhere between age 1 and 2, which is when the MMR vaccine is given. In a lot of cases, the symptoms manifest themselves before the jab, but often after (sometimes immediately after) it. This correlation is virtually a statistical certainty.
I really do understand people's concern about this issue - and the coincidence of the timing of the vaccine and the administration of the vaccination should not be ignored - they should prompt proper and serious research.
The thing is, they did. And the research overwhelmingly concludes that MMR vaccines do not cause, trigger or contribute towards autism. Parents will of course wonder whether the jab caused it, but like my friend, they learn ever more about autism (it's one hell of a journey - and far from a negative one), and come to the understanding that MMR is irrelevant to it.
Which leaves us (and the parents of your grandchildren) with a simple choice. Do we continue to worry about the correlation, and withdraw the vaccination, in the face of a worry which (whilst understandable) has been shown scientifically to be incorrect. Or do we let the children run the equally well known risks of catching and being seriously debilitated by (or killed by) measles, mumps or rubella ?
Given that we have coincidence and concern on one side of that choice, and expert scientific opinion on the other, don't we owe it to the children to go with the expert research on this ?
Could there be any greater conceit, than for someone to believe that the universe has to be simple enough for them to be able to understand it ?