Strengthening Post-Market Vaccine Safety Surveillance Globally: An Interpretive Description Study from Kenya, South Africa, and Canada

This interpretive description study across Kenya, South Africa, and Canada identifies key facilitators and barriers to post-market vaccine safety surveillance and research, highlighting the need for globally harmonized standards combined with locally tailored, patient-centered strategies and sustainable investments to strengthen infrastructure and workforce capacity.

The Gist

Imagine the global vaccination effort as a massive, high-speed train system. Before the train leaves the station (pre-licensure), engineers run thousands of tests to make sure the tracks are safe and the engine won't explode. But once the train is running at full speed with millions of passengers, new, rare problems can pop up—like a specific type of engine vibration that only happens on Tuesdays or a seat cushion that causes a rash in a very specific group of people.

This paper is a report from three different "stations" on this global train line: Canada (a high-income country with lots of resources), South Africa, and Kenya (both middle-income countries with different challenges). The researchers asked: "How well are we spotting these rare, post-trip problems, and how do we get people to help us investigate them?"

Here is the breakdown of their findings in simple terms:

1. The "Trust" Factor: The Feedback Loop

The biggest thing the researchers found is that reporting a problem is like sending a letter to a friend.

• The Good: If you send a letter and get a warm, helpful reply ("We heard you, we're looking into it, and here's how we can help"), you feel good and you'll write again if something else happens. In places where patients felt doctors listened and followed up, people reported side effects more often.
• The Bad: If you send a letter into a "black hole" and never hear back, or if your friend dismisses your concerns ("Oh, that's just stress, not the train"), you stop writing. In some cases, people felt their symptoms were ignored or blamed on other things (like stress or menstrual cycles), which made them lose trust in the system.

2. The "Digital Tools" Trap

All three countries tried to use apps and digital systems to make reporting easier, like upgrading from paper letters to instant messaging.

• The Promise: Apps like MedSafety (South Africa) and PvERS (Kenya) were supposed to make reporting fast and easy.
• The Reality: Just having the app isn't enough. In Kenya, people felt like they were "throwing things into a black hole" because the app didn't tell them what happened next. Also, the digital systems in different countries didn't always "talk" to each other, like having three different languages in one office. Sometimes, privacy laws were so strict that they accidentally slowed down the investigation, like putting a heavy lock on a door that was supposed to be open for emergencies.

3. The "Workforce" Bottleneck

Imagine a small team of mechanics trying to fix a broken train, but they are also trying to drive the train, sell tickets, and cook lunch for the passengers.

• The Problem: In all three countries, the people responsible for investigating side effects were overworked and under-staffed. In Canada, doctors were too busy with regular patients to follow up on vaccine reports. In Kenya and South Africa, there simply weren't enough people to do the detective work, and when staff left their jobs, the knowledge left with them.
• The Result: Important clues were missed because the system was too stretched to catch them.

4. Why People Join the Research (The "Why")

The study also asked people who had participated in vaccine studies: "Why did you do it?"

• The Hero Complex: Most people didn't join for money. They joined because they wanted to be heroes for their community. They felt a sense of duty to help science figure out the truth so others would be safe. It was like volunteering to be a test pilot to save the passengers on the next flight.
• The Hurdles: However, the process was often too complicated. The "permission slips" (consent forms) were written in confusing, legal language. People were worried about their private data being stolen. If the process felt like a maze, people got tired and walked away.

5. The Cultural "Weather"

The researchers found that culture and religion act like the weather for these reports.

• In some religious communities in Kenya, admitting you got sick after a vaccine felt like admitting you made a "bad choice," so people stayed silent to avoid shame.
• In other places, people relied on "home remedies" instead of going to the doctor, so the side effects never made it into the official system.

The Big Takeaway: What Needs to Happen?

The paper concludes that we can't just copy-paste solutions from rich countries to poorer ones, or vice versa. We need a hybrid approach:

1. Build the Foundation: We need to hire and train more people to do the detective work. You can't run a safety system with an empty team.
2. Fix the Tech: Digital tools are great, but they need to be user-friendly and actually give people feedback. Don't let them become "black holes."
3. Talk Human: Doctors and officials need to listen with empathy. If a patient says, "I feel sick," the answer shouldn't be "That's not the vaccine." It should be, "Let's figure this out together."
4. Simplify the Rules: The paperwork for research needs to be less scary and easier to understand, so people aren't afraid to help.

In short: To keep the global vaccination train safe, we need to stop treating safety reports as just "data points" and start treating them as human stories. We need to build systems that listen, respond, and care, whether you are in a high-tech hospital in Canada or a community clinic in Kenya.

Technical Summary

1. Problem Statement

Post-market vaccine safety surveillance is critical for detecting rare Adverse Events Following Immunization (AEFIs) that are often missed in pre-licensure clinical trials (e.g., myocarditis post-mRNA vaccination or thrombosis with thrombocytopenia syndrome post-adenoviral vector vaccination). However, significant disparities exist in surveillance infrastructure between High-Income Countries (HICs) and Low- and Middle-Income Countries (LMICs).

Key challenges include:

• Detection Difficulties: Rare AEFIs occur sporadically, making signal detection complex due to varying background rates across demographics and geographies.
• Infrastructure Gaps: Differences in diagnostic capacity, data accessibility, and biosample collection hinder the ability to investigate biological mechanisms and risk factors.
• Knowledge Gap: There is limited qualitative research on the clinical, social, and structural factors that enable or hinder AEFI investigation and research participation across diverse global settings.
• Biosample Collection: No single country possesses the capacity to collect sufficient biosamples for high-powered biomarker analyses, necessitating international harmonized networks.

2. Methodology

• Study Design: A qualitative multiple-case study using Interpretive Description methodology. This approach integrates clinical, experiential, and contextual knowledge to generate practical insights for policy.
• Study Sites: Three distinct jurisdictions representing different health system contexts:
  • Canada (HIC): University of Alberta / Canadian Special Immunization Clinic Network.
  • South Africa (LMIC): Wits-VIDA and Wits-ALIVE (University of the Witwatersrand).
  • Kenya (LMIC): KEMRI-Wellcome Trust Research Programme.
• Participants: A total of 92 participants were recruited via purposive and snowball sampling across three groups:
  1. Key Informants (KIs): 18 individuals in leadership roles (policy/surveillance).
  2. Healthcare Workers/Research Staff (HCW/RS): 47 individuals (clinical, lab, and research teams) involved in 5 focus group discussions.
  3. Past Participants (PP): 27 individuals who had previously participated in vaccine safety studies.
• Data Collection: Semi-structured interviews (30–60 mins) and focus group discussions (60–90 mins) conducted between late 2023 and mid-2025.
• Data Analysis: Thematic analysis following Braun and Clarke's six-phase framework. Transcripts were coded using NVivo and Dedoose. Rigor was ensured through cross-site collaborative analysis, stakeholder power mapping, and adherence to COREQ guidelines.

3. Key Contributions

The study provides a comparative, multi-stakeholder perspective on vaccine safety surveillance, moving beyond quantitative metrics to explore the human and systemic factors influencing surveillance efficacy.

• Cross-Contextual Comparison: It uniquely contrasts HIC and LMIC experiences, identifying that while HICs have better infrastructure, they face specific bureaucratic and coordination hurdles, whereas LMICs face structural resource constraints.
• Stakeholder Power Analysis: The study mapped the influence of diverse actors (politicians, community leaders, families, clinicians) on surveillance, highlighting that technical systems alone are insufficient without social capital and trust.
• Participant-Centric View: By including "Past Participants," the study integrates the patient perspective on reporting, trust, and research participation, which is often absent in surveillance literature.

4. Key Results

The analysis generated two overarching themes with four and three sub-themes respectively:

Theme 1: AEFI Surveillance and Investigation Across Contexts

• Trust in System Responsiveness: Reporting is a relational process. Participants reported higher willingness to report when they perceived the system as responsive (e.g., timely follow-up, empathy). Conversely, dismissal of symptoms (e.g., attributing myocarditis to stress) or lack of feedback (described as "throwing things into a black hole") eroded trust.
• Beliefs and Awareness: Reporting is influenced by how symptoms are framed. Normalization of side effects, reliance on home remedies, and social/religious stigma (e.g., fear of being seen as anti-vaccine) prevented reporting.
• Digital Innovation vs. Responsiveness: Digital tools (e.g., MedSafety App in SA, PvERS in Kenya) improved reporting accessibility but did not guarantee system responsiveness. Issues included lack of feedback loops, fragmented databases, and privacy laws that hindered data sharing for investigation.
• Implementation Gaps: While policies existed, operationalization failed due to:
  • Workforce Fragility: Overburdened staff, high turnover, and lack of dedicated time for surveillance.
  • Coordination Issues: Ambiguity in roles between federal/provincial agencies (Canada) and lack of clear diagnostic pathways (LMICs).
  • Resource Constraints: Limited access to diagnostic testing and funding in LMICs.

Theme 2: Vaccine Safety Research Participation and Conduct

• Motivators: Altruism and community-mindedness were primary drivers for participation across all sites. Participants viewed involvement as a civic duty to protect future generations and their communities.
• Logistics and Infrastructure: Convenience (e.g., saliva sampling, proximity to clinics) and financial compensation were critical enablers. Conversely, overcrowded clinics and staff turnover disrupted continuity.
• Institutional Policies and Privacy: Complex consent forms and concerns about data privacy (especially regarding genetic data) were significant barriers. In HICs, stringent ethics approval processes caused delays; in LMICs, a lack of individual counseling reduced informed consent quality.

5. Significance and Recommendations

The study underscores that effective global vaccine safety surveillance requires harmonized standards combined with locally tailored strategies.

Key Recommendations:

1. Human Resources: Invest in sustained funding for dedicated surveillance units and workforce training to prevent burnout and turnover.
2. Infrastructure: Develop integrated, interoperable digital reporting systems that provide feedback to reporters to build trust.
3. Communication: Implement culturally appropriate, multilingual campaigns leveraging trusted community leaders to address stigma and improve health literacy.
4. Research Governance: Streamline ethics approval processes (e.g., reciprocal approvals) and simplify consent forms to enhance participant understanding and trust.
5. Diagnostic Capacity: Strengthen local diagnostic capabilities to confirm AEFI diagnoses, particularly in LMICs.

Conclusion:
The paper concludes that while LMICs face critical resource barriers, HICs are not immune to systemic failures in coordination and responsiveness. Future models must be patient-centered, ethically grounded, and supported by sustainable investments in both digital infrastructure and human capital to maintain public trust in immunization programs globally.