Thimerosal, an Hg-preservative used in

early vaccines of 1980s and 1990s, killed infant brain cells, resulted in developmental defects such as autism. 

Today's kids immunization vaccines (at least in US) are free of thimerosal.  However, a lot of flu vaccines still contain thimerosal/ brain-damaging mercury. 

Of course vaccines themselves do not cause autism.  What an insult to human intelligence!