How Anti-Vaccine Sentiment Took Hold in the United States
The question is often whispered, the questioners sheepish. But increasingly, parents at the Central Park playground where Dr. Elizabeth A. Comen takes her young children have been asking her: “Do you vaccinate your kids?”
Dr. Comen, an oncologist who has treated patients for cancers related to the human papillomavirus that a vaccine can now prevent (for more on this, see p.33), replies emphatically: Absolutely.
She never imagined she would be getting such queries. Yet these playground exchanges are reflective of the national conversation at the end of the second decade of the 21st century — a time of stunning scientific and medical advances but also a time when the United States may, next month, lose its World Health Organization designation as a country that has eliminated measles, because of outbreaks this year. The W.H.O. has listed vaccine hesitancy as one of the top threats to global health.
As millions of families face back-to-school medical requirements and forms [this month], the contentiousness surrounding vaccines is heating up again, with possibly even more fervor…
In 1998, Andrew Wakefield, a British gastroenterologist, published a Lancet study (since discredited and withdrawn), associating the M.M.R. vaccine with autism.
Faced with risking autism or measles, some parents thought the answer was obvious. Most had never seen measles, mumps, or rubella because vaccines had nearly eliminated them. But they believed they knew autism.
And most people are notoriously poor at assessing risk, say experts in medical decision-making.
Many stumble on omission bias: “We would rather not do something and have something bad happen, than do something and have something bad happen,” explained Alison M. Buttenheim, an associate professor of nursing and health policy at the University of Pennsylvania School of Nursing.
People are flummoxed by numerical risk. “We pay more attention to numerators, such as ’16 adverse events,’ than we do to denominators, such as ‘per million vaccine doses,’” Dr. Buttenheim said.
A concept called “ambiguity aversion” is also involved, she added. “Parents would like to be told that vaccines are 100 percent safe,” she said. “But that’s not a standard we hold any medical treatment to.”
Relatively few people are absolutists about refusing all vaccines. “But if you’re uncertain about a decision, you’ll find those who confirm your bias and cement what you think,” said Rupali J. Limaye, a social scientist who studies vaccine behaviors at the Johns Hopkins Bloomberg School of Public Health.
Nowhere is that reinforcement more clamorous than on social media, Dr. Limaye added. “You may only see your pediatrician a few times a year but you can spend all day on the internet,” she said.
People tend to believe an individual’s anecdotal narrative over abstract numbers. By 2007, when Ms. McCarthy, the actress, insisted that vaccines caused her son’s autism, thousands found her to be more persuasive than data showing otherwise. A nascent movement took hold.
Excerpt from the original article by Jan Hoffman, published in The New York Times on September 23, 2019.