Objective To investigate the willingness to participate in vaccine clinical trials among permanent residents aged 18 years and older in Zhoushan city, Zhejiang province, and to analyze its influencing factors, so as to provide a reference for further improving residents' willingness to participate in vaccine clinical trials.

Methods From August to November 2024, 623 permanent residents aged 18 years and older were selected from two counties (districts) in Zhoushan city using a convenience sampling method. A questionnaire survey was conducted to collect information on socio-demographics, awareness of vaccine clinical trials, willingness to participate, and motivations. The willingness rate was calculated with the direct standardization method. Non-parametric tests were taken to analyze data between groups, and ordered logistic regression models were used to analyze the influencing factors of willingness to participate in vaccine clinical trials.

Results A total of 623 valid questionnaires were included. Eighty-one participants (13.00%) were willing to participate, 336 (53.93%) were conditionally willing to participate, and 206 (33.07%) were unwilling to participate. The standardized rate of willingness or conditional willingness to participate was 64.56%. Statistical differences were found between groups based on gender (Z = –2.883), occupation (Z = –2.282), awareness of vaccine clinical trials (Z = –5.731), and previous experience as a clinical trial participant (Z = –3.683) (all P < 0.05). Age group was correlated with willingness to participate (Rs = 0.092, P < 0.05). Ordered logistic regression analysis showed that gender, age, awareness, and previous experience as a clinical trial participant were influencing factors for willingness to participate in vaccine clinical trials.

Conclusions Male gender, age ≥ 60 years, low awareness, and lack of experience in clinical trials were associated with lower willingness to participate. It is recommended to objectively guide potential participants while improving their awareness, strengthen and improve the participant protection mechanism, and appropriately highlight altruistic motives to increase the actual enrollment rate.