Citizen involvement in scientific research: recruitment of volunteers for the “One Health Travel” study

Introduction The involvement of citizens in science is increasingly recognized as a valuable resource, especially for research data collection. However, volunteers’ engagement in study procedures and their retention over time can be challenging. The availability of detailed information on recruitment strategies applied for health-related citizen science (CS) projects is still limited. Here, the recruitment process of the “One Health Travel” study and the resulting enrolment and retention of volunteers is described to provide insights into potential barriers and facilitators of recruitment and to inform future CS research studies. Methods The “One Health Travel” study was a prospective observational study aiming to assess the risk of mosquito-, tick-bites and arbovirus exposures among travellers within Europe or to the Dutch Caribbean. Recruitment channels used were i) mass and social media campaigns, ii) targeted campaigns for nature-focused groups, iii) snowball sampling, vi) research consortium network, v) personal invitations. Results The enrolment target was met with 1,348 registrations over a 30-month period. However, this achievement required a modification of the recruitment strategy including, a lighter registration process and broader range of activities. Mass and social media, personal invitations and research consortium network recruited 506 (58.2%), 129 (14.8%), 94 (10.8%) participants, respectively. Their compliance to study procedures was between 84.4% and 89.4%. Most participants were female (605/870, 69.5%), and median age was 53. Discussion Mass and social media appeared to be an effective channel in terms of recruitment yield, given a tailored message and low-effort registration process. Most recruitment activities triggered only a short-term response. Therefore, timing of activities is an important factor to be considered.