The anti-vaccination movement regained attention due to actor Robert De Niro's decision late last week to pull the film "Vaxxed" from the Tribeca Film Festival, which he runs. But that doesn't mean the anti-vaccination movement will fade away anytime soon, experts say.
Despite the public pressure to pull the film — not to mention the innumerable studies showing that vaccines are safe — there are many reasons the movement persists, sociologists told Live Science.
"We know vaccines carry some risk, and we know that risk is very small," said Jennifer Reich, an associate professor of sociology at the University of Colorado Denver. "We also know that parents who distrust medical information are more likely to overestimate that risk and underestimate the risk of diseases." [10 Medical Myths That Just Won't Go Away]
Parents who decide not to vaccinate their children tend to be white, college-educated and high-income earners, said Reich, author of "Calling the Shots: Why Parents Reject Vaccines" (NYU Press, 2016).
The anti-vaccination viewpoint is a product of two colliding ideas, she said. One is the idea that "parents are in this alone," and that they're not responsible in any small way for other children in their community, Reich said. This means they don't feel it's important to contribute to herd immunity, which protects individuals who are unable to receive vaccines, she said.
The other idea is that individuals are solely responsible for their health, and that society bears no responsibility, for example, for encouraging people to go to the gym, participate in preventive care or avoid smoking.
Parents may take these ideas together, and view it as their duty to go it alone — to combine individualist parenting with individualized health care, Reich said. Many parents in this camp spend a substantial amount of time reading information and deciding whether it applies to their children, she said.
"They begin to doubt whether population data [on vaccine safety] applies to their own families, with their own lifestyle choices," Reich said.
For instance, a mother may think that if she breast-feeds her child, uses organic food and controls whom her child interacts with, then these efforts might protect the child from diseases. But this isn't the case, Reich said.
Many diseases, such as measles, are highly contagious, and "lots of viruses don't respond differently because of nutrition," so children may get sick even if they're breastfed and eat organic food, she said.
Other parents put faith in the body's natural ability to heal itself, Reich said. "They can see vaccines as potentially undermining the body's natural immune response," she said.
But people with this mind-set usually underestimate the severity of infectious diseases. For example, they typically think that if their child does get sick, he or she will not develop complications such as encephalitis or deafness. "They imagine they can control and heal their children through this kind of intensive parenting," Reich said.
It's hard to know how many parents are anti-vaccination, but kindergarten immunization records suggest that between 7 percent and 9 percent of U.S. children have been opted out of vaccines, and about 20 to 25 percent of children are deliberately undervaccinated (meaning they have not received all of the vaccines recommended for their age), Reich said. [5 Dangerous Vaccination Myths]
While writing her book, Reich spent eight years talking with anti-vaccination parents. Some parents were worried about the supposed vaccine-autism link (a connection that has been disproven countless times but is still featured in the film "Vaxxed"), she said. However, the majority of parents in the anti-vaccination camp told Reich that they had other concerns about vaccines' long-term negative health effects, despite evidence to the contrary.
These parents often wouldn't name a specific condition that concerned them, but said they were worried about autoimmune disorders in general, Reich said. In fact, many blamed the rise of autoimmune-disorder rates on vaccines. (Autoimmune disorders are diseases in which the immune system attacks the body's own cells; type 1 diabetes, celiac disease and lupus are examples.)
"I think that the anti-vaxxers live in a world that I would describe as anecdotal anxiety," meaning they become very worried after hearing or reading stories from other parents, said Jonathan Imber, a professor of sociology at Wellesley College who was not involved with Reich's research.
"They see a condition like autism, and they don't really have a sense of its causes," Imber told Live Science. And because the science is also unclear about why certain conditions develop, parents may look for purely anecdotal, and possibly inaccurate, explanations. These anecdotes may be "intensified by the material that is already out there," including distorted science, and further raise parents' anxieties, leading them not to vaccinate, Imber said.
Overall, both experts said there should be more transparency and communication about vaccination decisions and safety.
"I'm not sympathetic to people who are anti-vax, but I am sympathetic to the phenomena that it needs to be addressed more sympathetically," Imber said.
Copyright 2016 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.