When parents have concerns about the safety of childhood vaccinations, it can be tough to change their minds, as a new study shows.

The study involved “vaccine-hesitant” parents — a group distinct from the staunch “anti-vaxxer” crowd. They have worries about one or more routine vaccines, and question whether the benefits for their child are worthwhile.

Even though those parents are not “adamantly” opposed to vaccinations, it can still be hard for pediatricians to allay their concerns, said Jason Glanz, lead researcher on the study.

So Glanz and his colleagues looked at whether giving parents more information — online material “tailored” to their specific concerns — might help.

It didn’t. Parents who received the information were no more likely to have their babies up to date on vaccinations than other parents were, the study found.

The news was not all bad. Overall, more than 90% of babies in the study were all caught up on vaccinations.

So it may have been difficult to improve upon those numbers, according to Glanz, who is based at Kaiser Permanente Colorado’s Institute for Health Research in Aurora.

But, he said, it’s also possible the customized information reinforced some parents’ worries.

“It might have done more harm than good,” Glanz said.

That’s because among vaccine-hesitant parents, those who were directed to general information that was not tailored, had the highest vaccination rates — at 88%.

The findings were published online Oct. 12 in Pediatrics.

Childhood vaccination rates in the United States are generally high. But studies show that about 10% of parents either delay or refuse vaccinations for their kids — generally over safety worries.

Routine childhood vaccines have a long history of safe use, Glanz said, but some parents have questions. They may have heard that certain ingredients in vaccines are not safe, or worry that their baby is being given “too many” immunizations in a short time.

And during a busy pediatrician visit, Glanz said, it can be hard to address all those questions.

So his team tested a web-based tactic to augment routine checkups. They randomly assigned 824 pregnant women and new parents to one of three groups: One received standard vaccine information from their pediatrician; another was directed to the study website for additional, but general, information on immunizations; and the third received tailored information from the website.

That tailoring was done with the help of a survey that asked parents about their vaccine beliefs and concerns.

In the end, however, the targeted messaging flopped. It made no difference among parents overall: Across the three groups, between 91% and 93% of babies were up to date on vaccinations at 15 months of age.

And among the 98 parents who were deemed vaccine-hesitant, the tactic seemed to backfire: Only 67% of those babies were up to date compared to 88% of those whose parents received general vaccine information. The rate was 75% in the standard-care group.

Dr. Edgar Marcuse, an emeritus professor of pediatrics at the University of Washington School of Medicine in Seattle, wrote an editorial published with the study.

Like Glanz, he speculated that the targeted content may have “fanned the flames of doubt,” rather than quelling them.

It’s also possible, Marcuse said, that these types of questions are better addressed face-to-face than by “one-way” communication.

The question of how to sway vaccine-hesitant parents is always important, Marcuse said. And it has an added layer now, he noted, as health experts may encounter a wary public if and when a COVID-19 vaccine becomes available.

That vaccine would be brand-new, with only short-term data to back it up. But for routine childhood vaccinations, Marcuse said, the evidence supporting their effectiveness and safety is “overwhelming.”

Both he and Glanz urged parents to take any vaccine concerns to their doctor, rather than relying on what they find online.

Social media can be an especially powerful source of misinformation, Glanz noted.

“Your pediatrician is the best source of vaccine information — much better than social media,” he said.

More information

The American Academy of Pediatrics has more on childhood vaccine safety.

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