For years some parents and scientists have raised concerns about vaccine safety, including a possible link to autism and ADD. Many independent experts have sided with government officials and other scientists who say there's no possible connection. But how "independent" are they? CBS News investigative correspondent Sharyl Attkisson shares here's what she found.

They're some of the most trusted voices in the defense of vaccine safety: the American Academy of Pediatrics Every Child By Two , and pediatrician Dr. Paul Offit

But CBS News has found these three have something more in common - strong financial ties to the industry whose products they promote and defend.

The vaccine industry gives millions to the Academy of Pediatrics for conferences, grants, medical education classes and even helped build their headquarters. The totals are kept secret, but public documents reveal bits and pieces.

A $342,000 payment from Wyeth, maker of the pneumococcal vaccine - which makes $2 billion a year in sales.

A $433,000 contribution from Merck, the same year the academy endorsed Merck's HPV vaccine - which made $1.5 billion a year in sales.