The media took the bait, and despite Wakefield’s track record of dubious assertions and unverifiable lab results, they began churning out stories about how a maverick doctor was trying to protect innocent children against corrupt politicians and a rapacious pharmaceutical industry. Within months, vaccination rates across Western Europe began to fall, eventually jumping across the Atlantic to pockets of communities in the United States. (It’s now known that Wakefield’s work was partly funded by a firm handling vaccine litigation. In 2010, his medical license was revoked and The Lancet retracted his paper. This month, a British medical journal dubbed his study an “elaborate fraud.”)

Concerns over vaccines have been around ever since Edward Jenner used pus from a milkmaid’s cowpox blisters to inoculate an 8-year-old boy against smallpox in 1796, but these latest fears dated to two events of the late 1990s. The first came in 1998, when a British doctor named Andrew Wakefield published research in the medical journal The Lancet claiming he’d discovered a possible connection between the three-in-one measles-mumps-rubella (MMR) vaccine and autism. When his work was criticized, Wakefield said it was because the medical establishment was trying to discredit him.

Another common preoccupation, we discovered, was a gnawing anxiety that some shadowy force was pulling the wool over our collective eyes when it came to the true risks of vaccines. This caught us by surprise: Groups like the American Academy of Pediatrics and the American Medical Association weren’t organizations we thought likely to be part of a widespread conspiracy directed against the nation’s children.

My interest in the controversy began shortly after my wife and I were married in the fall of 2007. Though we were then childless, we found ourselves initiates in a culture in which people obsessed over issues about which we’d been blissfully unaware, like the political implications of disposable diapers and the merits of home births.

The evening went as you’d expect: There were some people I was genuinely happy to catch up with, a couple of awkward interactions with stumbling drunks, and some “Oh-my-God-is-that-really-her?” moments. There were also the inevitable 30-second recaps of the past 20 years of our lives: comparing career highlights, swapping baby pictures, trading new-parent war stories. In my case, those three things were intertwined: My son had just turned 1, and I was preparing for the publication of The Panic Virus, the product of more than two years’ research into debates about whether vaccines could be causing autism and other developmental disorders.

I spent the night after Thanksgiving at Saint, a Back Bay “ultra lounge” whose website features silhouettes of leggy women in high heels and seemingly not much else. This is not how my wife and I usually spend our nights out – but this was my 20-year Newton North High School reunion. I figured it couldn’t be any worse than dances in the school’s cafeteria, and I’d gone to plenty of those.

Then, in 1999, the Centers for Disease Control and Prevention and the American Academy of Pediatrics publicly recommended the removal of a widely used mercury-based preservative called thimerosal from childhood shots. Neither organization did a good job articulating the logic behind the decision, and in the absence of clear and reliable information, rumors about the dangers of thimerosal began mushrooming online.

Here, it was a small group of parents, dubbed the Mercury Moms, who pushed the issue into the public realm. At the time, the sharp rise in the number of autism diagnoses was driving awareness of the disease to all-time highs. (There’s still debate over whether this was due to an increase in cases or to a dramatic widening of the disease’s diagnostic criteria.) In spite of this attention, researchers were barely any closer to understanding autism’s origins or to finding a cure than they had been decades earlier. For parents of autistic children, this lack of knowledge resulted in feelings of hopelessness and frustration; for parents in general trying to determine the best course of action, it fueled a sense that medical experts and health authorities couldn’t be counted on to look out for their families’ well-being.

While the public health community’s response to these vaccine scares has arguably been inept, the scientific reaction has been considerably more decisive. By 2000, research teams worldwide had begun to study literally millions of children. And virtually all of the studies have shown the same thing: Neither thimerosal (which has been absent from all standard childhood vaccines since 2001) nor the MMR vaccine has any causal connection with autism. Unfortunately, journalists and broadcasters around the world haven’t let facts get in the way of a good story, and for years false claims made by self-anointed experts like Robert F. Kennedy Jr. and celebrities like Jenny McCarthy and Jim Carrey have gone largely unchallenged on outlets such as The Oprah Winfrey Show and Larry King Live.

The comments among my old high school classmates reflected this. Some told me they knew for a fact that vaccines caused autism. Others believed their doctors were telling the truth about vaccine safety. The majority, however, were basically agnostic – but, they’d say, there couldn’t be any harm in “alternative” vaccine schedules, like the one peddled by Dr. Robert Sears in his best-selling The Vaccine Book.

But, of course, there is harm. During my research, I met far too many parents whose personal experiences reflect this reality. Take, for example, Louisiana parents Danielle and Ralph Romaguera. Their 7-week-old daughter Gabrielle caught pertussis, or whooping cough, and died, only days away from receiving her first vaccination. The disease made a dramatic comeback last year, with outbreaks in areas across the country, including, most notably, California, where more than 7,000 people were infected and 10 infants died. Today, Danielle has made a commitment to counteracting the false information she sees in the media. “When I was in the hospital, I kept telling [Ralph], ‘Don’t you dare take a picture of her,’ ” Danielle says. “This is not how I want to remember my child. ... [But] sometimes I wish I had a picture to show people. That this is what happens to a child who comes down [with one of] these diseases.”

Just as I was finishing this book, my wife gave birth to our son. Like thousands of new parents around the world, vaccines scare me – but when I sneak into my child’s room at night to watch him sleep, I don’t worry that the MMR vaccine will cause autism or that the pertussis vaccine will lead to brain damage. Instead, I worry that he might come in contact with someone infected with measles before he’s old enough to have gotten all his shots. I worry that he’ll end up in a hospital bed because some parents decided the Internet was more trustworthy than their pediatrician.

As my son grows older, I hope that he learns the difference between critical thinking and getting swept up in a wave of unfounded hysteria, and I hope he considers the effects of his actions on those around him. Most of all, I hope he grows up in a world where science is acknowledged not as an ideology but as the best tool we have for understanding the universe, and where striving for the truth is recognized as the most noble quest humankind will ever undertake.

Adapted from The Panic Virus: A True Story of Medicine, Science, and Fear, by Seth Mnookin. Copyright © 2011 by Seth Mnookin. Send comments to magazine@globe.com.

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