那为啥CDC在国会听证会上承认所有的疫苗都没有controlled study呢？

"We have not studied vaccinated vs. unvaccinated."
- Dr. Boyle, CDC

In a hearing of the House Government Reform and Oversight Committee, Congressman Posey questions two officials, Dr. Guttmacher and Dr. Boyle, from the CDC over autism research. November 29, 2012.

"Rising Autism Rates: House Oversight and Government Reform Committee"
https://www.youtube.com/watch?v=uNWTOmEi_6A