Clinical Trial Recruitment Runs on Trust: Digital Ads Can’t Build it Alone

A person doesn't volunteer for a clinical trial because they saw an ad. They volunteer because something convinced them the research was real, the team was credible, and their concerns were addressed. Digital advertising can start that conversation, but it can't finish it alone.

I saw this play out while supporting recruitment for a first-of-its-kind Group A Streptococcus vaccine study at the University of Alberta. The research team needed 30 healthy participants for a two-stage trial targeting a disease that disproportionately affects children and marginalized communities. The campaign we built generated 93 leads in five weeks. But what made it work wasn't the ads in isolation; it was what surrounded them.

Posters from the Group A Streptococcus Vaccine Study worked alongside digital ads to exceed recruitment targets in just 5 weeks.

Digital advertising requires trust to achieve your objectives

Here's the challenge with relying on digital ads alone: a potential participant sees your ad, feels something, and then goes looking for confirmation that your study is legitimate. If all they find is another ad, you've likely lost them.

This is why the Rule of 7 matters more in clinical trial recruitment than in almost any other marketing context. The Rule of 7 states that a person typically needs to encounter your message seven times before they take action. In most marketing situations, those touchpoints build awareness and familiarity. In clinical trial recruitment, where you're asking someone to make a decision about their own health, they're doing something heavier. They're building the kind of trust that makes participation feel safe.

The question isn't whether you need multiple touchpoints. It's how to create them without blowing a budget that's probably already stretched thin.

The answer is likely already in your network

Most research teams have access to more communications channels than they realize. The challenge is that those channels tend to live in different departments or separate organizations, and nobody has connected them to the recruitment campaign.

This is where a coordinated approach makes a real difference. When we build digital recruitment materials for a study, we design them as a modular system from the start. That means the creative work that goes into your digital ads translates directly into print-ready posters, brochures, and social media assets that can travel through the networks your team already has access to. The incremental effort is small because the foundation is already built. What follows is a starting point for thinking about where those materials can go.

Where do you start? 

If you’re planning recruitment for a clinical trial, consider expanding your recruitment tactics to include partnerships with groups like those listed below. When approaching these groups, don't ask them to recruit for you. Ask organizations to educate their members. Framing the trial as a health resource or a new care option is far more effective when looking for partnerships.

Healthcare Providers & Clinical Staff

Doctors are an obvious starting point, but they're not always the most accessible. Pharmacists are the most frequently visited healthcare professionals in Canada, particularly among people managing chronic conditions, and they carry real community trust. Provincial pharmacy associations can help you reach pharmacies at scale through email campaigns, and many pharmacies are willing to include educational materials directly in their counselling booths.

Nurse practitioners are worth considering, too. They often have more time for patient education than physicians and can be genuine advocates for clinical research when they understand the study and believe in it.

Primary Care Networks and Health Teams are worth approaching directly. These networks distribute internal newsletters and host rounds presentations that reach hundreds of local practitioners. Getting featured in one of those can be worth more than most paid placements.

Disease-Specific Advocacy Groups

If your study is relevant to a specific condition, the advocacy organizations that serve that population have already done the trust-building work you're trying to do. National organizations like the Canadian Cancer Society, Diabetes Canada, and Heart and Stroke Foundation typically have local chapters that host events and communicate regularly with members who are motivated, informed, and often actively seeking ways to contribute to research.

The key to making these partnerships work is making participation easy for them. A pre-designed social media kit with ready-to-post graphics and copy, like the one we often include in our recruitment campaigns, means the organization doesn't have to do any creative work. They will share it because it genuinely serves their members, not because you asked them a favour.

These organizations have already built a bridge of trust specific to certain medical conditions.  If your research study focuses on or is relevant to a specific condition, these groups are a great way to educate potential participants and aid recruitment efforts.

Academic Institutions 

If your study is affiliated with a university, there are channels sitting unused that most research teams never think to activate. Student health services and campus clubs are useful if your study targets a younger demographic. Your university's communications department may be able to support you with faculty newsletters, press release distribution, or internal bulletin boards, often at no cost to the study.

For the Group A Strep vaccine trial,digital ads and on-campus posters drove the majority of leads. Digital ads reached a broad audience, while campus posters placed near the study location reached younger individuals who were already near the research site and receptive to university-related initiatives. The two channels reached overlapping but distinct audiences. Together, they helped the team exceed their stage one enrollment target and, and resulted in us pausing the campaign early to control the volume of leads.

Provincial SPOR Units (Strategy for Patient-Oriented Research)

CIHR (the Canadian Institutes of Health Research) funds provincial hubs specifically designed to bridge the gap between researchers and patients.

Regional units such as AbSPORU (Alberta), BC SPOR, or MSSU (Maritimes) often have established registries for public and patient engagement. These units can help you find patient partners to co-design your recruitment materials. In my experience, research teams that involve patient partners consistently develop messaging that is more effective and more relatable than teams that don't. It also aligns your study with the national mandate for patient-oriented research, which can help with future funding conversations.

Indigenous Health Authorities & Community Elders

If your study wants to include Indigenous participants, the process needs to start early with relationship-building. This can be done using the First Nations Principles of OCAP® (Ownership, Control, Access, and Possession), through dialogue with Community Elders or Health Directors. Don’t view this as a checklist item, but as committing to a process that respects Indigenous sovereignty and addresses the legitimate historical reasons for mistrust of research institutions. Getting this right takes more time upfront. It also produces better research.

A practical note on budget

The offline component of a recruitment campaign doesn't have to mean a significant additional investment. When we develop digital and print materials together, the work required to produce a poster, a brochure, or a social media kit for a partner organization is largely already done. The incremental cost is low. The reach it unlocks is not.

For research teams working within tight recruitment budgets, this is where the real efficiency lives: not in spending more on digital, but in making the digital investment work harder by surrounding it with touchpoints that reinforce the message in places where your audience already has reason to pay attention. When a potential participant sees your ad, then spots a poster at their clinic, then hears about the study from an advocacy group they trust, the decision to apply stops feeling like a risk. It starts feeling like the obvious next step.

Want a printable version of the stakeholder engagement toolkit? Download the guide.

If you’re interested in learning more about digital ads, read our post on what you need to know when using Meta for clinical trial advertising on Facebook or Instagram.