Though there is a great deal of scientific evidence to prove that vaccines are safe and effective, many parents in recent years have become skeptical of the childhood immunizations designed to prevent illness like measles, mumps, chickenpox, and even the flu. Efforts to encourage these parents to change their minds have most often focused on correcting the misinformation on which these beliefs are thought to be based. A new study by social science researchers, however, suggests that this approach may backfire.

Much of the distrust of vaccines can be traced back to a 1998 study in which British researcher Andrew Wakefield looked at the records of just one dozen autistic children and determined that the MMR (measles, mumps, and rubella) shot was the cause of their condition. The medical community was shocked by this assertion and many did not believe the findings (especially because the study was so small). It the coming years, a number of researchers attempted to recreate the study and no one could confirm his conclusion. Moreover, numerous other studies found no link between vaccines and autism, yet the popular press had already seized on the data, parents had been sufficiently whipped into a frenzy, and anti-vaccine groups and websites began sprouting up everywhere.

By the time the news hit in 2011 that Wakefield had a financial motive for coming to the conclusion that he did and that there was evidence that he had deliberately falsified information, the damage to the reputation of not just the MMR but all vaccines had been done. While public health experts scrambled to clarify the misinformation of the previous decade, anti-vaccine groups and celebrity spokespeople like Jenny McCarthy continued to suggest, despite evidence to the contrary, that vaccines were unsafe and led to autism. The results were frightening as the percentage of children who got vaccinated plummeted, and cases of long forgotten illnesses like mumps surged.

Those of us working in the sexual health field were also affected by the growing distrust as the vaccines to prevent the human papillomavirus (HPV) were released during this time. The HPV vaccine would have been a bit of a tough sell even without the doubt surrounding other inoculations, because parents sometimes fear that prevention efforts against sexually transmitted diseases—whether in the form of shots or condoms—will increase sexual behavior. Moreover, the Centers for Disease Control and Prevention (CDC) suggests that the shot be given starting at age 11 to ensure that all three required doses have been received before a young person becomes sexually active. Traditionally, parents don’t like to think about their children as even potential sexual beings, especially at such a young age. For these reasons and others, just 33.1 percent of girls ages 13 to 17 had received all recommended doses of the vaccine by 2012. (Though the CDC does now also recommend that boys be vaccinated, the early push was limited to girls).

So while other public health experts have spent the last decade trying to correct the misinformation about vaccine safety and the link to autism, sexual health experts have been providing similar information designed to reassure parents about the HPV vaccine specifically; it is safe and effective, it does not cause sexual activity, and it does prevent cancer. If this new study is correct, however, we may all be doing it wrong.

Researchers at Dartmouth College in New Hampshire surveyed over 1,700 parents to determine their beliefs about vaccines. Specifically, they wanted to know if the parents believed the idea that the MMR vaccine caused or could cause autism. After identifying the parents who believed this myth, the researchers tried one of four methods commonly used to correct such misbeliefs. Parents were either given information by a health authority that explained there was no connection, given information about the three diseases that the MMR vaccine protects against, shown pictures of kids suffering from these diseases, or told a story about a baby who almost died from the measles.

After being given this positive information about the vaccine, parents were less likely to believe that the MMR caused autism. Don’t get too excited, however, because the good news ends there. Despite their new-found faith in vaccines, these parents were less likely to say they would vaccinate their own child than they had been at the start of the study. When the study began, those parents who were strongly opposed to vaccines said that at best there was a 70 percent chance they’d vaccinate their children in the future. After being given the pro-vaccine information, this went down to 45 percent. (The study just measured intent to vaccinate, it did not follow the parents or children to see what actually happened.)

The researchers say further studies are needed to pin point the cause of this reaction but they think it is linked to self-esteem and self-image. If you are somebody who believes strongly in the link between autism and vaccines and you are presented with information that suggests your beliefs are wrong, your self-esteem and self-image may be shattered. One natural reaction to this is to dig in your heels, stick to your beliefs, and start looking for proof that you were right all along.

Lead researcher Brendan Nyhan explained to LiveScience, “We suggest that people are motivated to defend their more skeptical or less favorable attitudes towards vaccines.” Nyhan noted that as of yet we don’t really know what works to change their minds and said that as we search for new methods, “We shouldn’t put too much weight on the idea that there’s some magic message out there that will change people minds.”

I had my own experience trying to craft a persuasive argument to a skeptical parent just last week. We were sitting in the waiting room of my pediatrician’s office noting how different it was to bring a 3-year-old who was dancing around the waiting room loudly (me) and a 14-year-old who was curled in a chair eyes planted on her phone (her). The office assistant came up and gave her a brief written description of the vaccines her daughter was scheduled to get but said that it was obviously her choice. She held up the papers one after the other and said, “We’ll do this one but let’s hold off on this.” The nosy sex educator in me went on alert. I knew it had to be the HPV vaccine. I looked at her inquisitively and hoped that since we’d already been chatting, she would tell me what had just transpired. She picked up the cue and explained that she’d been intending for her daughter to get the HPV shot at this visit but just before she’d left the house she had checked email and a headline came through claiming a new study found that very vaccine unsafe. I asked her for details but she had none because she hadn’t read the article yet, just the headline. Still, she said, it seemed like a sign from the universe.

Despite the fact that it was really none of my business, I feel strongly about the benefits of the HPV vaccine (see this article for more) and could not let the chance to change even this one parent’s mind slip away. I scrambled for the right messages, facts, and tone. I tried to explain my “credentials” on the subject. Then said from all the research I’d done it was a really safe vaccine and added that it had been shown to be working, which was great because pretty much everyone our age has HPV. I tried to stay away from too much detail lest I sound like I was launching into a prepared diatribe. Ultimately, after making just a few points in the vaccine’s favor, I agreed that it was weird she should see that email at that very moment and said I could understand her seeing it as a “sign.” I ended by telling her she should talk to the regular doctor (who was out that day) because I know he is very pro-vaccines and she undoubtedly trusts him more than some random stranger in the waiting room who claims to be an expert.

She did not get her daughter vaccinated that day, and I will never know whether she does in the future. Still, I wonder whether my words had any impact. And after this study, I wonder if any words could have.

Though I find the results of this study—and the human nature that they spotlight—fascinating, I hope they are not too discouraging to those dedicated public health professional who have spent the last decade trying to convince parents that vaccinating their kids, whether against a host of childhood illness or HPV and cervical cancer, is the right thing to do. Yes, we just found out that it may be even harder to change somebody’s mind than we thought, but we have to keep on trying.