Chasing community immunity: the other 20%

Dr. Shannon MacDonald and her team tackle barriers to vaccination

08 October 2019


It's a loaded pejorative term that's gained traction over past decades as vaccination myths continue to plague public health professionals. It's a label at the heart of pitched battles between the scientific and health care communities on one hand, and parents who often don't know where to go for quality, trusted information on vaccines in a digital era of fake news and infinite source material on the other.

Not only does Dr. Shannon MacDonald hate the term "anti-vaxxer," but she sees media focus on people with deep-seated misgivings about vaccines as a missed opportunity. "What people don't realize is that data around vaccine uptake tells a very compelling story, and it's not the story most people imagine."

When discussing this vaccine uptake, many healthcare professionals reference the concept of "herd immunity," the threshold of vaccinations required to protect the small proportion of the population who cannot be vaccinated from deadly diseases and infections because of specific health-related conditions. "I prefer the term 'community immunity'," says MacDonald, emphasizing that vaccinations are about community health, implying that community-and relationships within our communities-are at the heart of why we vaccinate and what it means.

"There are real consequences to losing community immunity, especially for vulnerable, immuno-compromised people, such as kids being treated for cancer, or transplant patients who can't receive certain vaccines. Because they can't be vaccinated, they rely on their community to protect them from deadly infections and diseases through community immunity." Some of these diseases, such as pertussis (or whooping cough), are making a comeback, and the results for vulnerable and immuno-compromised people can be devastating.

To meet the "community immunity" threshold for the general population requires a 95% vaccination rate -a level that isn't being met with today's health systems, policies, and parental choices. Yet, we've only achieved immunization levels of approximately 75% for many childhood vaccines. This leaves 25% of children unvaccinated or not fully vaccinated. But, what isn't clear to most people-and becomes muddier with every so-called "anti-vaxxer" story-is why.

Given the media frenzy centred on people who actively oppose vaccinations because of strongly held convictions and deep-seated fears, many people believe these fears are the primary reason parents aren't vaccinating. Most are surprised to learn how small this number is relative to their high visibility in public discussion.

In fact, says MacDonald, only 5% of children are unvaccinated because their parents actively oppose vaccinations. So, what about that other 20%? That's where MacDonald's research team comes in.

"What people don't realize is that 20% of under-vaccinated kids come from families who don't hold strong beliefs about vaccinations," says MacDonald. "Many of them just have other reasons for not completing their vaccination schedules, such as barriers to access or competing demands on their time and resources."

Actually, MacDonald explains, the majority of unvaccinated kids fall into familiar patterns: for example, they come from families who move a lot, families with larger-than-average numbers of kids, and younger mothers.

When you start working with these families, MacDonald says many, if not most, have been partially vaccinated, but haven't completed their full vaccination schedule for a variety of reasons that have nothing to do with their belief systems.

"If a parent has an hourly wage job, it's harder to take time off for vaccinations. Or if they're moving locations a lot, they're going to be preoccupied." These parents want to do what's best for their kids and aren't necessarily opposed to vaccines, but in some cases, the more immediate demands of putting food on the table, managing childcare, or just generally dealing with life's many challenges come ahead of vaccination schedules.

In other words-the more barriers to access and competing demands on a given parent's plate, the less likely they are to vaccinate.

This is especially important for vulnerable groups who are hit with a double whammy of poor access to immunizations and higher vulnerability to disease or infection.

"There are big gaps in our knowledge about vaccines and at-risk groups," says MacDonald. "For example, we know virtually nothing about whether kids with frequent hospitalizations are getting vaccinated. And street-involved youth are at extremely high risk for HPV, whooping cough, and tetanus-we need more information about how to reach these kids, and more resources to meet them where they're at."

MacDonald and her team are doing research to bridge these gaps: identifying groups with sub-optimal immunization coverage, learning about their barriers to immunizations, and coming up with specialized strategies to improve vaccine uptake, tailored to the specific needs of these communities.

Doing this work is a collaborative effort. MacDonald emphasizes that her research success is all about working with the people who are actually involved in the vaccination process: both communities themselves, and the clinicians and policy makers who are using the information, data, and research her team generates.

She and her team thrive on this collaboration, even when it involves high levels of ongoing dialogue. "When a paediatric clinician comes to me with the question, I know their uptake of my study results will be faster," she says.

MacDonald adds that there are also a lot of parents who are hesitant to vaccinate because they are simply overwhelmed or confused and don't know where to turn. "Parents don't necessarily know what information sources are trustworthy, and this doesn't make them against vaccinations per se." By taking the specific needs of communities into account and focusing on addressing system-level barriers and supports, she believes our healthcare system can address this confusion and eliminate these barriers.

For some communities, this might mean changing where and how vaccines are distributed, taking vaccination clinics to places where people are already congregating. For others, it might mean creating a text message reminder system to make scheduling as easy as possible for busy, overwhelmed parents. The key is meeting communities where they're at, and addressing their specific barriers at the systems level.

At the heart of her research, MacDonald says, we need to start with the assumption that everyone wants to do the right thing for their children.

It's all about learning what makes specific groups less likely to vaccinate, and making the vaccination process straightforward, simple, and supported.

"At the end of the day, that's our job when it comes to vaccines: make the healthy choice the easy choice."