The need for long-term studies.

Robert F. Kennedy Jr.: "Let me just give you one quick other example. The most popular vaccine in the world is the DTP vaccine, diphtheria, tetanus, and pertussis. We banned, we got rid of it in this country because it was causing injuries, brain injuries, severe brain injuries or death to one in every 300 children."
"We used it in the 80s, and that's why there was all this litigation against vaccine companies that precipitated the passage of the Vaccine Act that then gave them immunity from liability, but... In Europe, they don't use it. In America, they don't use it. But we give it to 161 million African children a year."
"So Bill Gates asked the Danish government to support that program and said it saved 30 million lives. The Danish government said, show us the data. He wasn't able to. So they went to Africa and did their own studies. And they looked at 30 years of DTP data. And what they found shocked them all."
"They found that girls who got the DTP were dying at 10 times the rate of unvaccinated girls. But they were dying of things that nobody had ever associated with the vaccine. They were dying of anemia, malaria, bilharzia, pulmonary disease, respiratory disease, and pneumonia. And nobody noticed for 30 years that it was the vaccinated girls and not the unvaccinated girls who were dying."
"And what had happened is these girls were not dying of diphtheria, tetanus, and pertussis. The vaccine had protected them against those. But it had also ruined their immune systems. And they were unable to defend themselves against other just minor diseases that were that other kids who had hearty immune systems we're able to fend off."
"So that's why you need these long-term studies, and that's why I'm worried that we don't do that here in the United States."