Protecting babies and children against dangerous — sometimes fatal — diseases is a core mission of public health. Everyday, in health departments across the nation, someone is working on maintaining and improving childhood vaccination rates and keeping diseases like measles and mumps from regaining a foothold in the U.S.

Fortunately for us, public health has been so successful that it’s easy to forget what it was like just a few decades ago when measles was a common childhood illness. (Though here’s a reminder.) But sustaining vaccination rates that provide population-wide protection against disease is complicated work — and it’s complicated even more by growing hesitancy among some parents to vaccinate their children. Confronting that challenge in the age of the Internet is a sizeable task for public health, especially with research showing that simply relying on evidence-based talking points won’t always work and, in some cases, can even be counterproductive. That’s why finding an effective way to break through today’s clutter of information (and misinformation) to reach concerned parents is so important to sustaining current immunization rates.

In Washington state, where school entry vaccination exemptions had doubled over a decade and were three times higher than the national average, researchers have developed a promising way to do just that. Known as the Immunity Community, the intervention mobilizes vaccine-supportive parents and trains them to use positive dialogue to engage their peers, both in person and online, in discussions about vaccines. An evaluation of the three-year intervention, published last month in Health Promotion Practice, is very encouraging: parents who described themselves as “vaccine hesitant” fell from 23 percent to 14 percent, while parental concerns about their peers’ decisions not to vaccinate rose from 81 percent to 89 percent.

Clarissa Hsu, who helped design the intervention and co-authored the recent study, told me the key to Immunity Community was building off the positive experiences of parent vaccine advocates, rather than highlighting the differences between parents.

“We wanted to promote what’s already happening, which is that most parents do vaccinate,” said Hsu, who’s with the Kaiser Permanente Washington Health Research Institute’s Center for Community Health and Evaluation. “It wasn’t about attacking people’s beliefs, but about communicating positive messages about vaccines. …It allowed people to hear these messages without it being a direct confrontation.”

Vax Northwest, a public-private partnership that convened in 2008 to address vaccine hesitancy in Washington, developed the Immunity Community after early research identified parental social groups as promising intervention points for changing vaccine attitudes. Mackenzie Melton, immunization coordinator at WithinReach Washington, an organizational member of Vax Northwest, said those early focus groups revealed that while parents typically ranked health care providers as the most trusted source of vaccine information, their social networks of friends and family came second. As such, Immunity Community was developed to leverage the trust that parents already have within their social networks to create positive consensus around vaccines.

“The real thrust of the whole campaign was how to be immunization positive without being negative about people who don’t immunize,” Todd Faubion, immunization manager at WithinReach, told me. “We wanted (parent advocates) to talk about themselves — it was about them and how they can talk positively about immunizations.”

Immunity Community organizers worked with staff at schools, preschools and child care centers to recruit and train interested parents to become advocates in their communities. Recruits were then educated on basic vaccine science and trained on how to communicate effectively and respectfully with peers, organize immunization-positive activities, and engage fellow parents on social media.

“The emphasis was on the fact that (parent advocates) were trusted resources, not immunization experts,” Melton told me. “We wanted them to talk from the heart about why they thought (vaccines) were important for their families and communities. We didn’t want to dictate what (advocates) did — we wanted them to have the tools to have these conversations organically.”

Immunity Community was implemented in two communities: a suburban school district outside a major metro area and a small city in a rural county. In both, parent advocates engaged in a variety of immunization-positive activities, such as social media advocacy, hosting school events, passing out immunization materials and having one-on-one conversations with other parents. The evaluation in Health Promotion Practice, based on hundreds of survey responses from parents before and after the intervention, found that fewer parents thought children receive vaccines at too young an age, more parents were confident that vaccinating was a good idea, and more were aware of vaccination rates at their child’s school or day care. Also post-intervention, more parents agreed that vaccine ingredients were safe and more were concerned about fellow parents deciding not to vaccinate. Overall, the number of parents who identified as “vaccine hesitant” declined from 23 percent before the intervention to 14 percent after.

Study co-authors Hsu, Melton, Faubion, Jennie Schoeppe, Allen Cheadle, Creagh Miller and Juno Matthys write:

This study demonstrates the promise of a new and innovative approach to reducing vaccine hesitancy: engaging parent volunteers to be advocates in their own communities. The approach builds on findings that parents’ social networks are a strong predictor of vaccine acceptance and that likeable, trustworthy messengers are positively received. Results show statistically significant shifts in certain vaccine-related knowledge and attitudes among parents in prioritized communities. In order to test the long-term impacts of such a program, like decreased vaccine exemption rates, researchers must identify ways to accurately calculate immunization rates at participating sites, especially sites where there is no requirement to report to the state Department of Health.

In addition to changes in attitude, the Immunity Community also impacted statewide policy. Hsu reported that as a direct result of the intervention, officials enhanced recommendations guiding how cooperative preschools track immunization rates and disease outbreaks among their students. Hsu called the change, which affects more than 10,000 families, “a big win for public health.”

Of course, as with most studies, this one has its limitations. Hsu noted that because there was no control group with which to compare the Immunity Community effect, researchers can’t say whether the changes in parental attitudes were a direct result of the intervention. More research is needed to determine the long-term impact of Immunity Community on immunization behaviors, she told me. But one of the most promising results of the study, Hsu told me, is that “this is doable.” In other words, parents can be trained to be advocates for vaccines and their peers seem receptive to their vaccine-positive messaging approach.

“It created a new set of positive conversations around vaccines,” Hsu said. “I certainly think (Immunity Community) is a strategy that’s ready for people to try to implement elsewhere.”

Study co-author Faubion said while the formal evaluation process of Immunity Community is over, its advocates “remain strong and willing to step in when there’s an opportunity” to have a positive conversation about vaccines. Today, he said, Immunity Community is a publicly available resource for anyone in Washington state and beyond. To access its resources and assistance, contact Faubion and Melton at Vax Northwest.

“The whole idea was to create something innovative for public health officials,” Hsu said. “It’s critical that kids are vaccinated and that communities at-large understand herd immunity and how their decisions impact others.”

For a full copy of the Immunity Community study, visit Health Promotion Practice.

Kim Krisberg is a freelance public health writer living in Austin, Texas, and has been writing about public health for 15 years. Follow me on Twitter — @kkrisberg.