Until the summer of 2005, Sharon Kaufman had never paid much attention to the shifting theories blaming vaccines for a surge in reported cases of autism. Kaufman, a medical anthropologist at the University of California, San Francisco, knew that the leading health institutions in the United States had reviewed the body of evidence, and that they found no reason to think vaccines had anything to do with autism. But when she read that scientists and public officials who commented on the studies routinely endured malevolent emails, abusive phone calls, and even death threats, she took notice.
“Hecklers were issuing death threats to spokespeople,” Kaufman exclaims, “people who simply related the scientists' findings.” To a researcher with a keen eye for detecting major cultural shifts, these unsettling events signaled a deeper trend. “What happens when the facts of bioscience are relayed to the public and there is disbelief, lack of trust?” Kaufman wondered. “Where does that lead us?”
Struck by how the idea of a vaccine–autism link continued to gain cultural currency even as science dismissed it, Kaufman took a 26-month hiatus from her life's work on aging and longevity to investigate the forces fueling this growing divide between scientists and citizens (see Figure 1). She wanted to understand how parents thought about risk and experts, how these attitudes shaped parents' decisions about vaccination, and what the vaccine wars might teach us about the long-term erosion of public trust in science.
Key events in the US and Britain led parents in both countries to favor different, unproven vaccine–autism theories. In the UK, confidence in the measles, mumps, rubella (MMR) vaccine plummeted after British gastroenterologist Andrew Wakefield held a press conference to promote his hypothesis that the measles virus caused a leaky gut, sending toxic substances into the bloodstream and, ultimately, the brain. Separating the MMR into three individual vaccines would be safer, he said. Wakefield's idea expanded on a finding of intestinal disease in children with autism that was published in a now discredited 1998 Lancet paper . At press time of this Feature, Wakefield faces charges of serious professional misconduct before the General Medical Council (GMC) for allegedly violating ethical research practices on several counts. The GMC is also investigating allegations that Wakefield failed to disclose conflicts of interest—including a pending patent on a rival measles vaccine . (He has denied any wrongdoing.)
In the US, fears centered around the ethylmercury-containing preservative thimerosal after a 1999 government report revealed that three childhood vaccines—diphtheria, tetanus, acellular pertussis (DTaP); Haemophilus influenzae type b (Hib); and hepatitis B—might expose infants to more mercury than anyone had realized. (Thimerosal, 49.6% ethylmercury by weight, was never in vaccines with live attenuated virus, including MMR.) Based on this finding, a speculative article published in a fringe medical journal spawned the theory that autism might be a form of vaccine-induced mercury poisoning.
Now, more than ten years after unfounded doubts about vaccine safety first emerged, scientists and public health officials are still struggling to set the record straight. But as climate scientists know all too well, simply relating the facts of science isn't enough. No matter that the overwhelming weight of evidence shows that climate change is real, or that vaccines don't cause autism. When scientists find themselves just one more voice in a sea of “opinions” about a complex scientific issue, misinformation takes on a life of its own.