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.
Every Child By Two, a group that promotes early immunization for all children, admits the group takes money from the vaccine industry, too - but wouldn't tell us how much.
A spokesman told CBS News: "There are simply no conflicts to be unearthed." But guess who's listed as the group's treasurers? Officials from Wyeth and a paid advisor to big pharmaceutical clients.
Then there's Paul Offit, perhaps the most widely-quoted defender of vaccine safety.
He's gone so far as to say babies can tolerate "10,000 vaccines at once."
This is how Offit described himself in a previous interview: "I'm the chief of infectious disease at Children's Hospital of Philadelphia and a professor of pediatrics at Penn's medical school," he said.
Offit was not willing to be interviewed on this subject but like others in this CBS News investigation, he has strong industry ties. In fact, he's a vaccine industry insider.
Offit holds in a $1.5 million dollar research chair at Children's Hospital, funded by Merck. He holds the patent on an anti-diarrhea vaccine he developed with Merck, Rotateq, which has prevented thousands of hospitalizations.
And future royalties for the vaccine were just sold for $182 million cash. Dr. Offit's share of vaccine profits? Unknown.
The American Academy of Pediatrics, Every Child By Two and Dr. Offit would not agree to interviews, but all told us they're up front about the money they receive, and it doesn't sway their opinions.
Today's immunization schedule now calls for kids to get 55 doses of vaccines by age 6.
Ideally, it makes for a healthier society. But critics worry that industry ties could impact the advice given to the public about all those vaccines.