Eleanor and Mark Tremblay have trouble looking at their son, Oliver, who is 8 years old and severely autistic, without saying to themselves, "if only...."
As they play the videos showing how Ollie was before, they think, if only they could just rewind their lives; if only they could skip that shot: the measles, mumps and rubella vaccinations they believe caused their son's autism, although there is no conclusive evidence.
Dr. James Dale, a professor of medicine at the University of Tennessee's health science center in Memphis, has spent more than 30 years working to perfect a vaccine to prevent streptococcus, the infection that causes strep throat and, in its more virulent forms, so-called flesh-eating disease and rheumatic fever.
"There is risk with vaccines, but the benefits far, far outweigh the risks," Dr. Dale told Sunday Morning correspondent Martha Teichner. "If we can reduce the incidence of acute rheumatic fever and rheumatic heart disease by half in the world, that's where the real personal payoff would come."
On one side you have Dr. Dale, determined to save millions of children - and on the other, the Tremblays, heartbroken over the fate of one boy. Between them you have the story of vaccines: The greater good versus the risk, no matter how small, to the individual.
It's a debate that began in this country nearly three hundred years ago over smallpox.
"It was a disease that would sweep through cities and infect, you know, tens of thousands of people at a time, and it would kill 20, 30, 50 percent of them," said journalist Arthur Allen, the author of "Vaccine, the Controversial Story of Medicine's Greatest Lifesaver."
"The first form of smallpox vaccine came from China and India where it was used for centuries and it entered the U.S. in 1721. Cotton Mather actually brought it to the United States."
Mather was a hellfire and brimstone Puritan preacher from Boston. His house was firebombed when he urged Bostonians to try scratching live smallpox infection into their skin.
In 1796, British country doctor Edward Jenner confirmed that milkmaids, exposed to a much milder cowpox virus, were immune to smallpox. Millions of people finally dared to be vaccinated with Jenner's cowpox serum. The term vaccinate comes from the Latin word for cow, vacca.
"Confidence in vaccines and mistrust in vaccines goes in waves," Allen said. "And also, another element is really the seriousness of the disease. I mean, when the polio vaccine came out in 1955, it came into a country that was petrified of polio."
The conquest of polio became a national crusade.
"Millions of Americans participated in the March of Dimes," Allen said. "They literally sent their dimes to the White House."
In 1955, the announcement was made that Jonas Salk's polio vaccine worked. The fact that 200 people were paralyzed after getting the shot and ten died, was overlooked.
"Jonas Salk, you know, was a god," Allen said. "Church bells were ringing around the country. People were embracing in the street. It was a moment of unmitigated jubilation around the country."
Now they're protesting. Last month, there was a rally in Washington against the new human papilloma virus vaccine to prevent cervical cancer.