I was in secondary school when the Wakefield claims got in the news in the first place, and as it was (1) published in a reputable scientific journal and had not been retracted, and (2) he was still allowed to call himself "Doctor", many of us took it seriously and I opted out.
I did get the vaccine much later, when I realised my earlier fears were unfounded, but as a teenager time it seemed like a risk not worth taking — especially as I'd already had separate measles and rubella vaccines in early childhood, leaving only mumps.
I didn't realise that it was common for Brits to be refusing the MMR vaccine these days. Seems kind of stupid to me.
I also didn't realise how measles compromises the immune system - immune amnesia which was only discovered in 2012.