This is a summary, written by members of the CITF Secretariat, of:

Ravindran R, Szadkowski L, Lovblom LE, Clarke R, Huang QW, Manase D, Parente L, Walmsley S; STOPCoV research team. Decentralized study of COVID Vaccine Antibody Response (STOPCoV): Results of a participant satisfaction survey. PLOS Digit Health. 2023 May 9;2(5):e0000242. doi:

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

The digital research platform used by a CITF-funded study, Safety and Efficacy of Preventative COVID Vaccines (STOPCoV), was easy to use and popular, including among those aged 70+. Although only 33% of participants (ranging in age from 30 to above 70 years) had previously participated in clinical research, 95% were very satisfied with their participation and 90% indicated that they would participate in research again. The results were published in PLOS Digital Health. This study was led by Dr. Sharon Walmsley (University Health Network and University of Toronto).

The STOPCoV study was designed to assess the safety and efficacy of COVID-19 vaccines among those aged 70 and above compared to those 30- to 50-years-old in Ontario. In April 2022, a sub-study was initiated by researchers to determine participant satisfaction with the decentralized processes, the study website, and the collection and submission of study specimens.

Key findings:

  • The participants’ main reasons for involvement in the STOPCoV study were to learn about their own antibody response (68%), help others learn about the antibody response to COVID vaccines (76%), contribute to knowledge about vaccine safety (73%), and be able to take part in a clinical trial from their home (37%).
  • 90% of participants in both sex and age categories agreed or strongly agreed that the study website was easy to use. Both age cohorts agreed or strongly agreed that it was easy to log in and participate in the study using their electronic device.
  • 78% of participants reported little or no difficulty using lancets (the part that pricks the finger) in the dried blood spot (DBS) collection procedure, 90% found the frequency of DBS collection acceptable, and 75% indicated that their antibody results were presented in a way that was easy to understand.
  • A dedicated study email and phone line to contact the research team about concerns and obtain assistance, along with providing participants with their antibody levels at multiple timepoints, helped with retention and maintained participant engagement.

The participant satisfaction survey revealed how well-received was the decentralized approach to studying COVID vaccine antibody responses used in the STOPCoV study. These findings highlight the potential of decentralized studies to engage and retain participants, including those living in remote areas, by increasing accessibility and streamlining data collection processes. Real time, non-judgmental, and supportive communication, as well as clear instructions to participants, were among the keys to the study’s success.