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What eCOA Data Does a Vaccine Trial Actually Need to Capture?

Signant Health
Jun 19, 2026
Video
Participant dropout strategies in anti-obesity medication clinical trials

Vaccine trials generate a distinct data profile from other clinical trial types, with reactogenicity and immunogenicity measurements demanding real-time capture, high-frequency participant contact, and retention strategies that hold across seasonal windows.  

In this conversation, Dr. Stephan Bart, Executive Advisor for Infectious Disease and Vaccines at Signant Health and a Certified Physician Investigator with over 500 completed phase 1 through 3 trials, sets out what optimal eCOA design looks like for vaccine and infectious disease studies, drawing on direct experience supporting a pivotal trial of over 40,000 participants. 

Key Points 

  • Reactogenicity data, covering local events such as injection site pain, tenderness, redness, and swelling, and systemic events including fever, myalgia, arthralgia, and gastrointestinal symptoms, represent the primary safety dataset in vaccine trials and must be captured comprehensively in real-time post-exposure.
  • Immunogenicity assessment requires tracking both B cell response, which provides immediate antibody-based protection, and T cell response, which establishes cellular memory and determines how the body mounts a secondary response upon reintroduction of an infectious agent.
  • Vaccine trials can see hundreds or thousands of participants enroll within days during a pandemic, a data volume profile that differs fundamentally from linear enrolment in general medicine or CNS studies and requires technology built for that scale.
  • Blinded data analytics enable real-time identification of data outliers, sites requiring additional training, and potential data integrity issues, directing sponsor monitoring resources to where they are most needed.
  • eConsent supports participant understanding and retention by enabling site coordinators and investigators to ask probing comprehension questions during the consent process, reducing dropout of eligible participants before the trial begins.
  • The full video contains Dr. Bart's complete framework for eCOA instrument selection, patient engagement strategy across seasonal study windows, and the role of RTSM in managing breakthrough case supply logistics. 

Why It Matters Now: Vaccine Trial Data Demands Are Unlike Any Other Study Type 
 
For a participant in a vaccine trial, the post-exposure window is the moment that matters most. Reactogenicity events occur within hours and days of administration. Missing that data is not recoverable at a later visit.  
 
For sponsors, the stakes extend further: immunogenicity data must track protection levels across months, sometimes across two seasonal windows, to establish when a booster is warranted. A participant who leaves the study early takes that longitudinal evidence with them. 
 
The COVID-19 pandemic made these demands visible at a scale the industry had not previously encountered. Enrollment in some pivotal trials moved at a rate of thousands of participants per week. The data infrastructure required to manage that volume, maintain real-time safety visibility, and sustain participant contact across a multi-season protocol is not the same infrastructure that supports a standard phase 2 CNS or general medicine study. 
 
The FDA's accelerated approval pathway and Emergency Use Authorization process, applied under pressure during the pandemic, have since shaped regulatory expectations for evidence generation speed and data quality in infectious disease development. For sponsors designing vaccine programs today, those expectations are the baseline. 
 
What the Video Covers: Safety, Retention, and Data Integrity Across the Full Protocol 
 
Sponsors designing eCOA for vaccine trials have often approached instrument selection by adapting general oncology or CNS libraries, then discovering that the reactogenicity and immunogenicity parameters they need are not pre-built. Dr. Bart describes how a pre-validated eCOA library built specifically around regulatory authority-defined parameters reduces build time, lowers cost, and accelerates study start without requiring custom development for each new program. 
 
Beyond data capture, the video addresses the retention challenge that defines long-duration vaccine studies. Immunoglobulin responses to seasonal pathogens such as influenza or RSV must be tracked across the full protection window, which can span more than one annual cycle.  
 
Participant contact through eCOA, patient engagement tools, and telemedicine creates the sustained connection that holds participants in the protocol long enough to generate evidence. Dr. Bart is direct about why telemedicine adds what email and phone cannot: the investigator can see the participant, assess their condition, and align reported symptoms with clinical observation. 
 
For sponsors and CROs building eCOA and engagement strategy for an upcoming vaccine or infectious disease program, the full video provides the clinical reasoning and instrument selection logic behind each component of the recommended approach.
 
 

"When you look at pairing a good site with the good technology that Signant Health brings, it gives you a comprehensive solution. The more you contact, the more you're in touch. There's no better approach than being able to actually look at someone." - Stephan Bart, MD, Executive Advisor, Infectious Disease and Vaccines, Signant Health  

What eCOA endpoints are required in a vaccine clinical trial?

Vaccine trials require two primary endpoint categories. Reactogenicity captures local events at the injection site, including pain, tenderness, redness, swelling, and systemic events, including fever, myalgia, arthralgia, and gastrointestinal symptoms. Immunogenicity tracks B-cell antibody response for immediate protection and T-cell cellular memory response to assess duration of protection and booster timing. Both require real-time electronic capture post-exposure.

How do you maintain participant retention across a multi-season vaccine trial?

Retention in long-duration vaccine studies requires sustained participant contact across the full protocol window, which may span two seasonal cycles for pathogens such as influenza or RSV. eCOA provides the primary data collection touchpoint. Patient engagement tools maintain regular contact between visits. Telemedicine enables investigators to see participants directly, align symptom reports with clinical observation, and direct care, all of which support adherence and reduce dropout.

How does blinded data analytics support vaccine trial integrity?

Blinded data analytics in vaccine trials allows real-time identification of data outliers and site-level anomalies without unblinding the study. This directs sponsor monitoring to sites requiring additional training and flags potential data accuracy issues early. In high-volume enrolment scenarios, where hundreds of participants may enter a trial within days, this capability is critical to maintaining data quality at a scale that manual monitoring cannot match.

 
 

AUTHOR BIO 

Name: Stephan Bart 
Title and Credentials: MD, MD, is Executive Advisor for Infectious Disease and Vaccines at Signant Health
Bio: Stephan Bart, MD, is Executive Advisor for Infectious Disease and Vaccines at Signant Health. He is both board certified and a Certified Physician Investigator with a broad therapeutic scope, having completed more than 500 domestic and international phase 1 through 3 clinical trials. He has held faculty positions at Penn State University and the University of Maryland Medical Center, published in peer-reviewed journals, and is recognized as a key opinion leader in vaccine and immunology research.  

This conversation is hosted by Dawie Wessels, MD, Chief Medical Officer at Signant Health. 

 

Designing eCOA and patient engagement strategy for an upcoming vaccine or infectious disease program? Speak to Stephan Bart, MD, about reactogenicity capture, immunogenicity tracking, and participant retention across multi-season protocols. 

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