But although millions benefit, even the safest vaccines aren't safe for everyone.
Because of genetic differences, some people are harmed by vaccines "that almost everybody else responds to just fine," said Dr. Robert W. Block, former chairman of a federal advisory panel on childhood vaccines.
And some have paid a terrible price. For example, until 2000, when the U.S. switched from the oral live polio vaccine to inactivated polio shots, the vaccine itself caused a few polio cases each year.
Gordon Pierson, a 12-year-old in Jackson, Tenn., contracted polio as an infant this way and is paralyzed and unable to speak.
"We were doing what we thought was best for our son, and the exact opposite happened," said his father, Randy Pierson. "We were just heartbroken, and we are every day."
Fear of legal fallout inspired the National Vaccine Injury Compensation Act. At the time, vaccine makers were facing a surge in claims, mainly from adverse reactions to the diphtheria-pertussis-tetanus, or DPT, vaccine. An exodus from the market and shortages seemed possible. In response, Congress decreed that instead of suing vaccine makers, people would first have to seek compensation from the new vaccine court.
Health and Human Services officials would administer the trust fund and screen petitions, deciding whether to concede or oppose each claim. Justice Department lawyers would appear in court on their behalf.
Petitioners could not seek awards for punitive damages or losses to family members as they could in civil court. But they were to benefit from greater speed and flexibility, and a lower burden of proof. Moreover, the program typically would pay petitioners' legal costs once the case was over, win or lose.
However, what was meant to be a win-win proposition instead has been mostly "a stupendous success in protecting the industry," said George Washington University law professor Peter H. Meyers, who directs a group of law students who represent petitioners. As for helping victims, he said, the record is "much more spotty."
Some see this as a natural result of federal health officials' fierce devotion to the immunization program -- and their fear that if enough injuries were acknowledged, people would be afraid to get their shots.
Universal immunization is a fundamental mission of Health and Human Services. One of its branches, the Food and Drug Administration, licenses vaccines, and another, the CDC, promotes their use with such slogans as "Vaccination: An Act of Love."
