I guess during your extensive research you would have seen that the prime determinant for the MMR take up was the Lancet article that linked it to autism, which was partially retracted in 2004 and fully in 2010. Rates then rose from around 80% peaking at 93% in 2013/14.
Out of interest, given that take up rates were over 90% at the time of your son's stated 2nd birthday did you follow the science or your opinion or would you rather not say whether he "has had" it?
https://www.nuffieldtrust.org.uk/res...-and-mothers-1