A few years ago, while reporting a story on attention deficit disorder, I asked an affluent young mother why she was spending thousands of dollars on a dubious therapy, rather than on treatment proven to be effective. "I did my research on the Internet," she replied, citing a handful of pseudoscientific Web sites that advocated the "natural" approach she favored and that warned against immunizing her preschoolers against childhood diseases because the shots contained toxic ingredients.

I thought of her while reading "The Panic Virus," journalist Seth Mnookin's disturbing and well-told chronicle of the childhood vaccine wars in the United States and England. While Mnookin traces the history of vaccines, beginning with the one for smallpox, his focus is on the specious but remarkably persistent myth that the current roster of shots children receive to prevent diseases such as measles, whooping cough and hepatitis B can cause autism or other serious problems - and that this "fact" is well-known to government officials, pediatricians and vaccine manufacturers, who have conspired to cover it up.

A contributing editor for Vanity Fair, Mnookin became interested in the subject in 2008 shortly after getting married and becoming part of a community of young professionals who drove Priuses, shopped at Whole Foods and decided against vaccinating their children, which they considered to be a health-conscious choice. Some didn't trust the medical establishment, while others were swayed by media reports about the possible dangers of vaccines or thought that the number of shots given to children is excessive.

Ironically, immunizations have become victims of their own success, eradicating from public memory the devastating aftermaths of once-common pediatric illnesses: deafness caused by mumps, blindness after measles and paralysis brought on by polio. Mnookin documents how these vaccines, a cornerstone of modern public health, have become targets of fear and misinformation. He draws on interviews with anti-vaccine activists and public health officials, scientific literature, media accounts, and research into the psychology of risk. His view of the media's role is unsparing; he shows how ratings-hungry news and entertainment shows kept the debate alive, even as evidence for the safety and effectiveness of the shots became overwhelming.

Opposition to childhood vaccines simmered mostly on the fringes until 1998, when London gastroenterologist Andrew Wakefield co-authored a study in the British medical journal Lancet linking autism to the measles, mumps and rubella (MMR) shot. Although his research was immediately challenged, it was not until last year that the study was retracted and Wakefield stripped of his medical license. Two weeks ago the British Medical Journal published an investigative article on the study, as well as an editorial calling it "an elaborate fraud" based on falsified data. The influential journal reported that crucial details in the case histories of the dozen children included in Wakefield's report had been altered or were misrepresented.

In the years after Wakefield's study, the anti-vaccine argument gained significant traction, especially on the Internet, which has become an important source of health information for many people. As a consequence, immunization rates on both sides of the Atlantic dropped; outbreaks of measles, pertussis and mumps increased; and some children died of vaccine-preventable diseases. Even though study after study failed to find a link between the ingredients in vaccines and autism, health officials in the United States and England seemed unable to effectively refute anti-immunization arguments, for reasons that remain puzzling.

Mnookin's contention that the controversy would not have achieved staying power without uncritical or at times blatantly irresponsible reporting by numerous media outlets - including NBC, the Huffington Post, Rolling Stone and The Washington Post - is persuasive. Too often, he writes, journalists display "a willingness to parrot quack claims under the guise of reporting on citizen concerns." Much of the coverage failed to adequately explain the fundamental but essential difference between correlation and causation. Simply because a child received a vaccine and soon after began showing signs of autism does not mean the shot caused the disorder, only that the two events are linked temporally. Nor can scientists ever say categorically that vaccines do not cause autism; it is impossible to prove a negative.

Television talk shows also provided a platform for vaccine opponents to make their case, largely unchallenged. During an appearance on "Oprah," actress Jenny McCarthy blamed the MMR shot for her son's autism, proudly telling the audience, "The University of Google is where I got my degree."

This book effectively documents the isolation and anguish of parents raising an autistic child, and it's hard not to feel that these families are victims of a battle that has squandered significant resources. A former leader who has broken with one prominent autism group over its anti-vaccine stance said it best: "At some point, you have to say, 'This question has been asked and answered and it's time to move on.' "



A True Story of Medicine,

Science, and Fear

By Seth Mnookin

Simon & Schuster. 429 pp. $26.99

Sandra G. Boodman, a former staff writer for The Washington Post, writes about health and medicine.