First off: anyone with a functioning brain should be pro-vaccines.
Secondly, something is definitely up with autism, diagnoses have increased
by 150% since 2000. That is way higher than simply increased awareness and diagnosis.
I think the explanation is maternal stress during pregnancy. Overall stress levels are on the rise in the US due to longer working hours and stagnant wages, and there are several research studies that stress during pregnancy is associated with ADHD, anxiety disorders and autism-like behaviors in infants and children.
https://www.ncbi.nlm.nih.gov/pubmed/28681538
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3153828/
Probably more I could link but people can do the research themselves, we talked about this stuff during my MA program.