I did some research years ago and found that A Blood Types are more vulnerable to metals including mercury in vaccinations. I have had a child since my A blood type child was vaccine damaged and came down with Autism. My next child was also A Blood Type. She has never been vaccinated and has never had anything but a runny nose a couple of days and mild allergies in her 7 years. I totally researched it though. Everyone should do the research and discover for themselves what vaccines do for your child's bloodtype and other genetic pre-dispositions.